Package 'survey'

Description

A method for the anova function, for use on svyglm and svycoxph objects. With a single model argument it produces a sequential anova table, with two arguments it compares the two models.

Usage

## S3 method for class 'svyglm'
anova(object, object2 = NULL, test = c("F", "Chisq"), 
 method = c("LRT", "Wald"), tolerance = 1e-05, ..., force = FALSE)
## S3 method for class 'svycoxph'
anova(object, object2=NULL,test=c("F","Chisq"),
 method=c("LRT","Wald"),tolerance=1e-5,...,force=FALSE)
## S3 method for class 'svyglm'
AIC(object,...,k=2, null_has_intercept=TRUE)
## S3 method for class 'svyglm'
BIC(object,...,maximal)
## S3 method for class 'svyglm'
extractAIC(fit,scale,k=2,..., null_has_intercept=TRUE)
## S3 method for class 'svrepglm'
extractAIC(fit,scale,k=2,..., null_has_intercept=TRUE)

Arguments

Details

The reference distribution for the LRT depends on the misspecification effects for the parameters being tested (Rao and Scott, 1984). If the models are symbolically nested, so that the relevant parameters can be identified just by manipulating the model formulas, anova is equivalent to regTermTest.If the models are nested but not symbolically nested, more computation using the design matrices is needed to determine the projection matrix on to the parameters being tested. In the examples below, model1 and model2 are symbolically nested in model0 because model0 can be obtained just by deleting terms from the formulas. On the other hand, model2 is nested in model1 but not symbolically nested: knowing that the model is nested requires knowing what design matrix columns are produced by stype and as.numeric(stype). Other typical examples of models that are nested but not symbolically nested are linear and spline models for a continuous covariate, or models with categorical versions of a variable at different resolutions (eg, smoking yes/no or smoking never/former/current).

A saddlepoint approximation is used for the LRT with numerator df greater than 1.

AIC is defined using the Rao-Scott approximation to the weighted loglikelihood (Lumley and Scott, 2015). It replaces the usual penalty term p, which is the null expectation of the log likelihood ratio, by the trace of the generalised design effect matrix, which is the expectation under complex sampling. For computational reasons everything is scaled so the weights sum to the sample size.

BIC is a BIC for the (approximate) multivariate Gaussian models on regression coefficients from the maximal model implied by each submodel (ie, the models that say some coefficients in the maximal model are zero) (Lumley and Scott, 2015). It corresponds to comparing the models with a Wald test and replacing the sample size in the penalty by an effective sample size. For computational reasons, the models must not only be nested, the names of the coefficients must match.

extractAIC for a model with a Gaussian link uses the actual AIC based on maximum likelihood estimation of the variance parameter as well as the regression parameters.

Value

Object of class seqanova.svyglm if one model is given, otherwise of class regTermTest or regTermTestLRT

Note

At the moment, AIC works only for models including an intercept.

References

Rao, JNK, Scott, AJ (1984) "On Chi-squared Tests For Multiway Contingency Tables with Proportions Estimated From Survey Data" Annals of Statistics 12:46-60.

Lumley, T., & Scott, A. (2014). "Tests for Regression Models Fitted to Survey Data". Australian and New Zealand Journal of Statistics, 56 (1), 1-14.

Lumley T, Scott AJ (2015) "AIC and BIC for modelling with complex survey data" J Surv Stat Methodol 3 (1): 1-18.

See Also

regTermTest, pchisqsum

Examples

data(api)
dclus2<-svydesign(id=~dnum+snum, weights=~pw, data=apiclus2)

model0<-svyglm(I(sch.wide=="Yes")~ell+meals+mobility, design=dclus2, family=quasibinomial())
model1<-svyglm(I(sch.wide=="Yes")~ell+meals+mobility+as.numeric(stype), 
     design=dclus2, family=quasibinomial())
model2<-svyglm(I(sch.wide=="Yes")~ell+meals+mobility+stype, design=dclus2, family=quasibinomial())

anova(model2)	
anova(model0,model2)					     		    
anova(model1, model2)

anova(model1, model2, method="Wald")

AIC(model0,model1, model2)
BIC(model0, model2,maximal=model2)

## AIC for linear model is different because it considers the variance
## parameter

model0<-svyglm(api00~ell+meals+mobility, design=dclus2)
model1<-svyglm(api00~ell+meals+mobility+as.numeric(stype), 
     design=dclus2)
model2<-svyglm(api00~ell+meals+mobility+stype, design=dclus2)
modelnull<-svyglm(api00~1, design=dclus2)

AIC(model0, model1, model2)

AIC(model0, model1, model2,modelnull, null_has_intercept=FALSE)

## from ?twophase
data(nwtco)
dcchs<-twophase(id=list(~seqno,~seqno), strata=list(NULL,~rel),
        subset=~I(in.subcohort | rel), data=nwtco)
a<-svycoxph(Surv(edrel,rel)~factor(stage)+factor(histol)+I(age/12), design=dcchs)
b<-update(a, .~.-I(age/12)+poly(age,3))
## not symbolically nested models
anova(a,b)

Description

The Academic Performance Index is computed for all California schools based on standardised testing of students. The data sets contain information for all schools with at least 100 students and for various probability samples of the data.

Usage

data(api)

Format

The full population data in apipop are a data frame with 6194 observations on the following 37 variables.

cds

Unique identifier

stype

Elementary/Middle/High School

name

School name (15 characters)

sname

School name (40 characters)

snum

School number

dname

District name

dnum

District number

cname

County name

cnum

County number

flag

reason for missing data

pcttest

percentage of students tested

api00

API in 2000

api99

API in 1999

target

target for change in API

growth

Change in API

sch.wide

Met school-wide growth target?

comp.imp

Met Comparable Improvement target

both

Met both targets

awards

Eligible for awards program

meals

Percentage of students eligible for subsidized meals

ell

‘English Language Learners’ (percent)

yr.rnd

Year-round school

mobility

percentage of students for whom this is the first year at the school

acs.k3

average class size years K-3

acs.46

average class size years 4-6

acs.core

Number of core academic courses

pct.resp

percent where parental education level is known

not.hsg

percent parents not high-school graduates

hsg

percent parents who are high-school graduates

some.col

percent parents with some college

col.grad

percent parents with college degree

grad.sch

percent parents with postgraduate education

avg.ed

average parental education level

full

percent fully qualified teachers

emer

percent teachers with emergency qualifications

enroll

number of students enrolled

api.stu

number of students tested.

The other data sets contain additional variables pw for sampling weights and fpc to compute finite population corrections to variance.

Details

apipop is the entire population, apisrs is a simple random sample, apiclus1 is a cluster sample of school districts, apistrat is a sample stratified by stype, and apiclus2 is a two-stage cluster sample of schools within districts. The sampling weights in apiclus1 are incorrect (the weight should be 757/15) but are as obtained from UCLA.

Source

Data were obtained from the survey sampling help pages of UCLA Academic Technology Services; these pages are no longer on line.

References

The API program has been discontinued at the end of 2018, and the archive page at the California Department of Education is now gone. The Wikipedia article has links to past material at the Internet Archive. https://en.wikipedia.org/wiki/Academic_Performance_Index_(California_public_schools)

Examples

library(survey)
data(api)
mean(apipop$api00)
sum(apipop$enroll, na.rm=TRUE)

#stratified sample
dstrat<-svydesign(id=~1,strata=~stype, weights=~pw, data=apistrat, fpc=~fpc)
summary(dstrat)
svymean(~api00, dstrat)
svytotal(~enroll, dstrat, na.rm=TRUE)

# one-stage cluster sample
dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)
summary(dclus1)
svymean(~api00, dclus1)
svytotal(~enroll, dclus1, na.rm=TRUE)

# two-stage cluster sample
dclus2<-svydesign(id=~dnum+snum, fpc=~fpc1+fpc2, data=apiclus2)
summary(dclus2)
svymean(~api00, dclus2)
svytotal(~enroll, dclus2, na.rm=TRUE)

# two-stage `with replacement'
dclus2wr<-svydesign(id=~dnum+snum, weights=~pw, data=apiclus2)
summary(dclus2wr)
svymean(~api00, dclus2wr)
svytotal(~enroll, dclus2wr, na.rm=TRUE)


# convert to replicate weights
rclus1<-as.svrepdesign(dclus1)
summary(rclus1)
svymean(~api00, rclus1)
svytotal(~enroll, rclus1, na.rm=TRUE)

# post-stratify on school type
pop.types<-xtabs(~stype, data=apipop)

rclus1p<-postStratify(rclus1, ~stype, pop.types)
dclus1p<-postStratify(dclus1, ~stype, pop.types)
summary(dclus1p)
summary(rclus1p)

svymean(~api00, dclus1p)
svytotal(~enroll, dclus1p, na.rm=TRUE)

svymean(~api00, rclus1p)
svytotal(~enroll, rclus1p, na.rm=TRUE)

Description

This function creates an object to store the number of clusters sampled within each stratum (at each stage of multistage sampling) and the number of clusters available in the population. It is called by svydesign, not directly by the user.

Usage

as.fpc(df, strata, ids,pps=FALSE)

Arguments

Details

The population size information may be specified as the number of clusters in the population or as the proportion of clusters sampled.

Value

An object of class survey_fpc

See Also

svydesign,svyrecvar

Description

Creates a replicate-weights survey design object from a traditional strata/cluster survey design object. JK1 and JKn are jackknife methods, BRR is Balanced Repeated Replicates and Fay is Fay's modification of this, bootstrap is Canty and Davison's bootstrap, subbootstrap is Rao and Wu's $(n-1)$ bootstrap, and mrbbootstrap is Preston's multistage rescaled bootstrap. With a svyimputationList object, the same replicate weights will be used for each imputation if the sampling weights are all the same and separate.replicates=FALSE.

Usage

as.svrepdesign(design,...)
## Default S3 method:
as.svrepdesign(design, type=c("auto", "JK1", "JKn", "BRR", "bootstrap",
   "subbootstrap","mrbbootstrap","Fay"),
   fay.rho = 0, fpc=NULL,fpctype=NULL,..., compress=TRUE, 
   mse=getOption("survey.replicates.mse"))
## S3 method for class 'svyimputationList'
as.svrepdesign(design, type=c("auto", "JK1", "JKn", "BRR", "bootstrap",
   "subbootstrap","mrbbootstrap","Fay"),
   fay.rho = 0, fpc=NULL,fpctype=NULL, separate.replicates=FALSE, ..., compress=TRUE, 
   mse=getOption("survey.replicates.mse"))

Arguments

Value

Object of class svyrep.design.

References

Canty AJ, Davison AC. (1999) Resampling-based variance estimation for labour force surveys. The Statistician 48:379-391

Judkins, D. (1990), "Fay's Method for Variance Estimation," Journal of Official Statistics, 6, 223-239.

Preston J. (2009) Rescaled bootstrap for stratified multistage sampling. Survey Methodology 35(2) 227-234

Rao JNK, Wu CFJ. Bootstrap inference for sample surveys. Proc Section on Survey Research Methodology. 1993 (866–871)

See Also

brrweights, svydesign, svrepdesign, bootweights, subbootweights, mrbweights

Examples

data(scd)
scddes<-svydesign(data=scd, prob=~1, id=~ambulance, strata=~ESA,
nest=TRUE, fpc=rep(5,6))
scdnofpc<-svydesign(data=scd, prob=~1, id=~ambulance, strata=~ESA,
nest=TRUE)

# convert to BRR replicate weights
scd2brr <- as.svrepdesign(scdnofpc, type="BRR")
scd2fay <- as.svrepdesign(scdnofpc, type="Fay",fay.rho=0.3)
# convert to JKn weights 
scd2jkn <- as.svrepdesign(scdnofpc, type="JKn")

# convert to JKn weights with finite population correction
scd2jknf <- as.svrepdesign(scddes, type="JKn")

## with user-supplied hadamard matrix
scd2brr1 <- as.svrepdesign(scdnofpc, type="BRR", hadamard.matrix=paley(11))

svyratio(~alive, ~arrests, design=scd2brr)
svyratio(~alive, ~arrests, design=scd2brr1)
svyratio(~alive, ~arrests, design=scd2fay)
svyratio(~alive, ~arrests, design=scd2jkn)
svyratio(~alive, ~arrests, design=scd2jknf)

data(api)
## one-stage cluster sample
dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)
## convert to JK1 jackknife
rclus1<-as.svrepdesign(dclus1)
## convert to bootstrap
bclus1<-as.svrepdesign(dclus1,type="bootstrap", replicates=100)

svymean(~api00, dclus1)
svytotal(~enroll, dclus1)

svymean(~api00, rclus1)
svytotal(~enroll, rclus1)

svymean(~api00, bclus1)
svytotal(~enroll, bclus1)

dclus2<-svydesign(id = ~dnum + snum, fpc = ~fpc1 + fpc2, data = apiclus2)
mrbclus2<-as.svrepdesign(dclus2, type="mrb",replicates=100)
svytotal(~api00+stype, dclus2)
svytotal(~api00+stype, mrbclus2)

Description

The structure of survey design objects changed in version 2.9, to allow standard errors based on multistage sampling. as.svydesign converts an object to the new structure and .svycheck warns if an object does not have the new structure.

You can set options(survey.want.obsolete=TRUE) to suppress the warnings produced by .svycheck and options(survey.ultimate.cluster=TRUE) to always compute variances based on just the first stage of sampling.

Usage

as.svydesign2(object)
.svycheck(object)

Arguments

Value

Object of class survey.design2

See Also

svydesign, svyrecvar

Description

Draws a barplot or dotplot based on results from a survey analysis. The default barplot method already works for results from svytable.

Usage

## S3 method for class 'svystat'
barplot(height, ...)
## S3 method for class 'svrepstat'
barplot(height, ...)
## S3 method for class 'svyby'
barplot(height,beside=TRUE, ...)

## S3 method for class 'svystat'
dotchart(x,...,pch=19)
## S3 method for class 'svrepstat'
dotchart(x,...,pch=19)
## S3 method for class 'svyby'
dotchart(x,...,pch=19)

Arguments

Examples

data(api)
dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)

a<-svymean(~stype, dclus1)
barplot(a)
barplot(a, names.arg=c("Elementary","High","Middle"), col="purple", 
  main="Proportions of school level")

b<-svyby(~enroll+api.stu, ~stype, dclus1, svymean)
barplot(b,beside=TRUE,legend=TRUE)
dotchart(b)

Description

Bootstrap weights for infinite populations ('with replacement' sampling) are created by sampling with replacement from the PSUs in each stratum. subbootweights() samples n-1 PSUs from the n available (Rao and Wu), bootweights samples n (Canty and Davison).

For multistage designs or those with large sampling fractions, mrbweights implements Preston's multistage rescaled bootstrap. The multistage rescaled bootstrap is still useful for single-stage designs with small sampling fractions, where it reduces to a half-sample replicate method.

Usage

bootweights(strata, psu, replicates = 50, fpc = NULL,
         fpctype = c("population", "fraction", "correction"),
         compress = TRUE)
subbootweights(strata, psu, replicates = 50, compress = TRUE)
mrbweights(clusters, stratas, fpcs, replicates=50, 
         multicore=getOption("survey.multicore"))

Arguments

Value

A set of replicate weights

warning

With multicore=TRUE the resampling procedure does not use the current random seed, so the results cannot be exactly reproduced even by using set.seed()

Note

These bootstraps are strictly appropriate only when the first stage of sampling is a simple or stratified random sample of PSUs with or without replacement, and not (eg) for PPS sampling. The functions will not enforce simple random sampling, so they can be used (approximately) for data that have had non-response corrections and other weight adjustments. It is preferable to apply these adjustments after creating the bootstrap replicate weights, but that may not be possible with public-use data.

References

Canty AJ, Davison AC. (1999) Resampling-based variance estimation for labour force surveys. The Statistician 48:379-391

Judkins, D. (1990), "Fay's Method for Variance Estimation" Journal of Official Statistics, 6, 223-239.

Preston J. (2009) Rescaled bootstrap for stratified multistage sampling. Survey Methodology 35(2) 227-234

Rao JNK, Wu CFJ. Bootstrap inference for sample surveys. Proc Section on Survey Research Methodology. 1993 (866–871)

See Also

as.svrepdesign

https://bschneidr.github.io/svrep/ for other sorts of replicate weights

Description

Compute replicate weights from a survey design. These functions are usually called from as.svrepdesign rather than directly by the user.

Usage

brrweights(strata, psu, match = NULL,
              small = c("fail","split","merge"),
              large = c("split", "merge", "fail"),
              fay.rho=0, only.weights=FALSE,
              compress=TRUE, hadamard.matrix=NULL)
jk1weights(psu,fpc=NULL,
              fpctype=c("population","fraction","correction"),
              compress=TRUE)
jknweights(strata,psu, fpc=NULL,
              fpctype=c("population","fraction","correction"),
              compress=TRUE,
              lonely.psu=getOption("survey.lonely.psu"))

Arguments

Details

JK1 and JKn are jackknife schemes for unstratified and stratified designs respectively. The finite population correction may be specified as a single number, a vector with one entry per stratum, or a vector with one entry per observation (constant within strata). When fpc is a vector with one entry per stratum it may not have names that differ from the stratum identifiers (it may have no names, in which case it must be in the same order as unique(strata)). To specify population stratum sizes use fpctype="population", to specify sampling fractions use fpctype="fraction" and to specify the correction directly use fpctype="correction"

The only reason not to use compress=TRUE is that it is new and there is a greater possibility of bugs. It reduces the number of rows of the replicate weights matrix from the number of observations to the number of PSUs.

In BRR variance estimation each stratum is split in two to give half-samples. Balanced replicated weights are needed, where observations in two different strata end up in the same half stratum as often as in different half-strata.BRR, strictly speaking, is defined only when each stratum has exactly two PSUs. A stratum with one PSU can be merged with another such stratum, or can be split to appear in both half samples with half weight. The latter approach is appropriate for a PSU that was deterministically sampled.

A stratum with more than two PSUs can be split into multiple smaller strata each with two PSUs or the PSUs can be merged to give two superclusters within the stratum.

When merging small strata or grouping PSUs in large strata the match variable is used to sort PSUs before merging, to give approximate matching on this variable.

If you want more control than this you should probably construct your own weights using the Hadamard matrices produced by hadamard

Value

For brrweights with only.weights=FALSE a list with elements

For jk1weights and jknweights a data frame of replicate weights and the scale and rscale arguments to svrVar.

References

Levy and Lemeshow "Sampling of Populations". Wiley.

Shao and Tu "The Jackknife and Bootstrap". Springer.

See Also

hadamard, as.svrepdesign, svrVar, surveyoptions

Examples

data(scd)
scdnofpc<-svydesign(data=scd, prob=~1, id=~ambulance, strata=~ESA,
nest=TRUE)

## convert to BRR replicate weights
scd2brr <- as.svrepdesign(scdnofpc, type="BRR")
svymean(~alive, scd2brr)
svyratio(~alive, ~arrests, scd2brr)

## with user-supplied hadamard matrix
scd2brr1 <- as.svrepdesign(scdnofpc, type="BRR", hadamard.matrix=paley(11))
svymean(~alive, scd2brr1)
svyratio(~alive, ~arrests, scd2brr1)

Description

Calibration, generalized raking, or GREG estimators generalise post-stratification and raking by calibrating a sample to the marginal totals of variables in a linear regression model. This function reweights the survey design and adds additional information that is used by svyrecvar to reduce the estimated standard errors.

Usage

calibrate(design,...)
## S3 method for class 'survey.design2'
calibrate(design, formula, population,
       aggregate.stage=NULL, stage=0, variance=NULL,
       bounds=c(-Inf,Inf), calfun=c("linear","raking","logit"),
       maxit=50,epsilon=1e-7,verbose=FALSE,force=FALSE,trim=NULL,
       bounds.const=FALSE, sparse=FALSE,...)
## S3 method for class 'svyrep.design'
calibrate(design, formula, population,compress=NA,
       aggregate.index=NULL, variance=NULL, bounds=c(-Inf,Inf),
       calfun=c("linear","raking","logit"),
       maxit=50, epsilon=1e-7, verbose=FALSE,force=FALSE,trim=NULL,
       bounds.const=FALSE, sparse=FALSE,...)
## S3 method for class 'twophase'
calibrate(design, phase=2,formula, population,
       calfun=c("linear","raking","logit","rrz"),...)
grake(mm,ww,calfun,eta=rep(0,NCOL(mm)),bounds,population,epsilon, 
  verbose,maxit,variance=NULL)
cal_names(formula,design,...)

Arguments

Details

The formula argument specifies a model matrix, and the population argument is the population column sums of this matrix. The function cal_names shows what the column names of this model matrix will be.

For the important special case where the calibration totals are (possibly overlapping) marginal tables of factor variables, as in classical raking, the formula and population arguments may be lists in the same format as the input to rake.

If the population argument has a names attribute it will be checked against the names produced by model.matrix(formula) and reordered if necessary. This protects against situations where the (locale-dependent) ordering of factor levels is not what you expected.

Numerical instabilities may result if the sampling weights in the design object are wrong by multiple orders of magnitude. The code now attempts to rescale the weights first, but it is better for the user to ensure that the scale is reasonable.

The calibrate function implements linear, bounded linear, raking, bounded raking, and logit calibration functions. All except unbounded linear calibration use the Newton-Raphson algorithm described by Deville et al (1993). This algorithm is exposed for other uses in the grake function. Unbounded linear calibration uses an algorithm that is less sensitive to collinearity. The calibration function may be specified as a string naming one of the three built-in functions or as an object of class calfun, allowing user-defined functions. See make.calfun for details.

The bounds argument can be specified as global upper and lower bounds e.g bounds=c(0.5, 2) or as a list with lower and upper vectors e.g. bounds=list(lower=lower, upper=upper). This allows for individual boundary constraints for each unit. The lower and upper vectors must be the same length as the input data. The bounds can be specified as multiplicative values or constant values. If constant, bounds.const must be set to TRUE.

Calibration with bounds, or on highly collinear data, may fail. If force=TRUE the approximately calibrated design object will still be returned (useful for examining why it failed). A failure in calibrating a set of replicate weights when the sampling weights were successfully calibrated will give only a warning, not an error.

When calibration to the desired set of bounds is not possible, another option is to trim weights. To do this set bounds to a looser set of bounds for which calibration is achievable and set trim to the tighter bounds. Weights outside the bounds will be trimmed to the bounds, and the excess weight distributed over other observations in proportion to their sampling weight (and so this may put some other observations slightly over the trimming bounds). The projection matrix used in computing standard errors is based on the feasible bounds specified by the bounds argument. See also trimWeights, which trims the final weights in a design object rather than the calibration adjustments.

For two-phase designs calfun="rrz" estimates the sampling probabilities using logistic regression as described by Robins et al (1994). estWeights will do the same thing.

Calibration may result in observations within the last-stage sampling units having unequal weight even though they necessarily are sampled together. Specifying aggegrate.stage ensures that the calibration weight adjustments are constant within sampling units at the specified stage; if the original sampling weights were equal the final weights will also be equal. The algorithm is as described by Vanderhoeft (2001, section III.D). Specifying aggregate.index does the same thing for replicate weight designs; a warning will be given if the original weights are not constant within levels of aggregate.index.

In a model with two-stage sampling, population totals may be available for the PSUs actually sampled, but not for the whole population. In this situation, calibrating within each PSU reduces with second-stage contribution to variance. This generalizes to multistage sampling. The stage argument specifies which stage of sampling the totals refer to. Stage 0 is full population totals, stage 1 is totals for PSUs, and so on. The default, stage=NULL is interpreted as stage 0 when a single population vector is supplied and stage 1 when a list is supplied. Calibrating to PSU totals will fail (with a message about an exactly singular matrix) for PSUs that have fewer observations than the number of calibration variables.

The variance in the calibration model may depend on covariates. If variance=NULL the calibration model has constant variance. If variance is not NULL it specifies a linear combination of the columns of the model matrix and the calibration variance is proportional to that linear combination. Alternatively variance can be specified as a vector of values the same length as the input data specifying a heteroskedasticity parameter for each unit.

The design matrix specified by formula (after any aggregation) must be of full rank, with one exception. If the population total for a column is zero and all the observations are zero the column will be ignored. This allows the use of factors where the population happens to have no observations at some level.

In a two-phase design, population may be omitted when phase=2, to specify calibration to the phase-one sample. If the two-phase design object was constructed using the more memory-efficient method="approx" argument to twophase, calibration of the first phase of sampling to the population is not supported.

In a two-phase design, formula may be a glm or lm or coxph model fitted to the phase-one data. Calibration will be done using the influence functions of this model as the calibration variables.

Value

A survey design object.

References

Breslow NE, Lumley T, Ballantyne CM, Chambless LE, Kulich M. Using the whole cohort in the analysis of case-cohort data. Am J Epidemiol. 2009;169(11):1398-1405. doi:10.1093/aje/kwp055

Deville J-C, Sarndal C-E, Sautory O (1993) Generalized Raking Procedures in Survey Sampling. JASA 88:1013-1020

Kalton G, Flores-Cervantes I (2003) "Weighting methods" J Official Stat 19(2) 81-97

Lumley T, Shaw PA, Dai JY (2011) "Connections between survey calibration estimators and semiparametric models for incomplete data" International Statistical Review. 79:200-220. (with discussion 79:221-232)

Sarndal C-E, Swensson B, Wretman J. "Model Assisted Survey Sampling". Springer. 1991.

Rao JNK, Yung W, Hidiroglou MA (2002) Estimating equations for the analysis of survey data using poststratification information. Sankhya 64 Series A Part 2, 364-378.

Robins JM, Rotnitzky A, Zhao LP. (1994) Estimation of regression coefficients when some regressors are not always observed. Journal of the American Statistical Association, 89, 846-866.

Vanderhoeft C (2001) Generalized Calibration at Statistics Belgium. Statistics Belgium Working Paper No 3.

See Also

postStratify, rake for other ways to use auxiliary information

twophase and vignette("epi") for an example of calibration in two-phase designs

survey/tests/kalton.R for examples replicating those in Kalton & Flores-Cervantes (2003)

make.calfun for user-defined calibration distances.

trimWeights to trim final weights rather than calibration adjustments.

Examples

data(api)
dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)

cal_names(~stype, dclus1)

pop.totals<-c(`(Intercept)`=6194, stypeH=755, stypeM=1018)

## For a single factor variable this is equivalent to
## postStratify

(dclus1g<-calibrate(dclus1, ~stype, pop.totals))

svymean(~api00, dclus1g)
svytotal(~enroll, dclus1g)
svytotal(~stype, dclus1g)

## Make weights constant within school district
(dclus1agg<-calibrate(dclus1, ~stype, pop.totals, aggregate=1))
svymean(~api00, dclus1agg)
svytotal(~enroll, dclus1agg)
svytotal(~stype, dclus1agg)


## Now add sch.wide
cal_names(~stype+sch.wide, dclus1)
(dclus1g2 <- calibrate(dclus1, ~stype+sch.wide, c(pop.totals, sch.wideYes=5122)))

svymean(~api00, dclus1g2)
svytotal(~enroll, dclus1g2)
svytotal(~stype, dclus1g2)

## Finally, calibrate on 1999 API and school type

cal_names(~stype+api99, dclus1)
(dclus1g3 <- calibrate(dclus1, ~stype+api99, c(pop.totals, api99=3914069)))

svymean(~api00, dclus1g3)
svytotal(~enroll, dclus1g3)
svytotal(~stype, dclus1g3)


## Same syntax with replicate weights
rclus1<-as.svrepdesign(dclus1)

(rclus1g3 <- calibrate(rclus1, ~stype+api99, c(pop.totals, api99=3914069)))

svymean(~api00, rclus1g3)
svytotal(~enroll, rclus1g3)
svytotal(~stype, rclus1g3)

(rclus1agg3 <- calibrate(rclus1, ~stype+api99, c(pop.totals,api99=3914069), aggregate.index=~dnum))

svymean(~api00, rclus1agg3)
svytotal(~enroll, rclus1agg3)
svytotal(~stype, rclus1agg3)


###
## Bounded weights
range(weights(dclus1g3)/weights(dclus1))
dclus1g3b <- calibrate(dclus1, ~stype+api99, c(pop.totals, api99=3914069),bounds=c(0.6,1.6))
range(weights(dclus1g3b)/weights(dclus1))

svymean(~api00, dclus1g3b)
svytotal(~enroll, dclus1g3b)
svytotal(~stype, dclus1g3b)

## Individual boundary constraints as constant values
# the first weight will be bounded at 40, the rest free to move
bnds <- list(
  lower = rep(-Inf, nrow(apiclus1)), 
  upper = c(40, rep(Inf, nrow(apiclus1)-1))) 
head(weights(dclus1g3))
dclus1g3b1 <- calibrate(dclus1, ~stype+api99, c(pop.totals, api99=3914069), 
  bounds=bnds, bounds.const=TRUE)
head(weights(dclus1g3b1))
svytotal(~api.stu, dclus1g3b1)

## trimming
dclus1tr <- calibrate(dclus1, ~stype+api99, c(pop.totals, api99=3914069), 
   bounds=c(0.5,2), trim=c(2/3,3/2))
svymean(~api00+api99+enroll, dclus1tr)
svytotal(~stype,dclus1tr)
range(weights(dclus1tr)/weights(dclus1))

rclus1tr <- calibrate(rclus1, ~stype+api99, c(pop.totals, api99=3914069),
   bounds=c(0.5,2), trim=c(2/3,3/2))
svymean(~api00+api99+enroll, rclus1tr)
svytotal(~stype,rclus1tr)

## Input in the same format as rake() for classical raking
pop.table <- xtabs(~stype+sch.wide,apipop)
pop.table2 <- xtabs(~stype+comp.imp,apipop)
dclus1r<-rake(dclus1, list(~stype+sch.wide, ~stype+comp.imp),
               list(pop.table, pop.table2))
gclus1r<-calibrate(dclus1, formula=list(~stype+sch.wide, ~stype+comp.imp), 
     population=list(pop.table, pop.table2),calfun="raking")
svymean(~api00+stype, dclus1r)
svymean(~api00+stype, gclus1r)


## generalised raking
dclus1g3c <- calibrate(dclus1, ~stype+api99, c(pop.totals,
    api99=3914069), calfun="raking")
range(weights(dclus1g3c)/weights(dclus1))

(dclus1g3d <- calibrate(dclus1, ~stype+api99, c(pop.totals,
    api99=3914069), calfun=cal.logit, bounds=c(0.5,2.5)))
range(weights(dclus1g3d)/weights(dclus1))



## Ratio estimators are calibration estimators
dstrat<-svydesign(id=~1,strata=~stype, weights=~pw, data=apistrat, fpc=~fpc)
svytotal(~api.stu,dstrat)

common<-svyratio(~api.stu, ~enroll, dstrat, separate=FALSE)
predict(common, total=3811472)

pop<-3811472
## equivalent to (common) ratio estimator
dstratg1<-calibrate(dstrat,~enroll-1, pop, variance=1)
svytotal(~api.stu, dstratg1)

# Alternatively specifying the heteroskedasticity parameters directly
dstratgh <- calibrate(dstrat,~enroll-1, pop, variance=apistrat$enroll)
svytotal(~api.stu, dstratgh)

Description

Many replicate weight matrices have redundant rows, such as when weights are the same for all observations in a PSU. This function produces a compressed form. Methods for as.matrix and as.vector extract and expand the weights.

Usage

compressWeights(rw, ...)
## S3 method for class 'svyrep.design'
compressWeights(rw,...)
## S3 method for class 'repweights_compressed'
as.matrix(x,...)
## S3 method for class 'repweights_compressed'
as.vector(x,...)

Arguments

Value

An object of class repweights_compressed or a svyrep.design object with repweights element of class repweights_compressed

See Also

jknweights,as.svrepdesign

Examples

data(api)
dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)
rclus1c<-as.svrepdesign(dclus1,compress=TRUE)
rclus1<-as.svrepdesign(dclus1,compress=FALSE)

Description

Computes confidence intervals for regression parameters in svyglm objects. The default is a Wald-type confidence interval, adding and subtracting a multiple of the standard error. The method="likelihood" is an interval based on inverting the Rao-Scott likelihood ratio test. That is, it is an interval where the working model deviance is lower than the threshold for the Rao-Scott test at the specified level.

Usage

## S3 method for class 'svyglm'
confint(object, parm, level = 0.95, method = c("Wald", "likelihood"), ddf = NULL, ...)

Arguments

Value

A matrix of confidence intervals

References

J. N. K. Rao and Alistair J. Scott (1984) On Chi-squared Tests For Multiway Contigency Tables with Proportions Estimated From Survey Data. Annals of Statistics 12:46-60

See Also

confint

Examples

data(api)
dclus2<-svydesign(id=~dnum+snum, fpc=~fpc1+fpc2, data=apiclus2)

m<-svyglm(I(comp.imp=="Yes")~stype*emer+ell, design=dclus2, family=quasibinomial)
confint(m)
confint(m, method="like",ddf=NULL, parm=c("ell","emer"))

Description

A tiny dataset from the VPLX manual.

Usage

data(crowd)

Format

A data frame with 6 observations on the following 5 variables.

rooms

Number of rooms in the house

person

Number of people in the household

weight

Sampling weight

cluster

Cluster number

stratum

Stratum number

Source

Manual for VPLX, Census Bureau.

Examples

data(crowd)

## Example 1-1
i1.1<-as.svrepdesign(svydesign(id=~cluster, weight=~weight,data=crowd))
i1.1<-update(i1.1, room.ratio=rooms/person,
overcrowded=factor(person>rooms))
svymean(~rooms+person+room.ratio,i1.1)
svytotal(~rooms+person+room.ratio,i1.1)
svymean(~rooms+person+room.ratio,subset(i1.1,overcrowded==TRUE))
svytotal(~rooms+person+room.ratio,subset(i1.1,overcrowded==TRUE))

## Example 1-2
i1.2<-as.svrepdesign(svydesign(id=~cluster,weight=~weight,strata=~stratum, data=crowd))
svymean(~rooms+person,i1.2)
svytotal(~rooms+person,i1.2)

Description

dimnames returns variable names and row names for the data variables in a design object and dim returns dimensions. For multiple imputation designs there is a third dimension giving the number of imputations. For database-backed designs the second dimension includes variables defined by update. The first dimension excludes observations with zero weight.

Usage

## S3 method for class 'survey.design'
dim(x)
## S3 method for class 'svyimputationList'
dim(x)
## S3 method for class 'survey.design'
dimnames(x)
## S3 method for class 'DBIsvydesign'
dimnames(x)
## S3 method for class 'svyimputationList'
dimnames(x)

Arguments

Value

A vector of numbers for dim, a list of vectors of strings for dimnames.

See Also

update.DBIsvydesign, with.svyimputationList

Examples

data(api)
dclus1 <- svydesign(ids=~dnum,weights=~pw,data=apiclus1,fpc=~fpc)
dim(dclus1)
dimnames(dclus1)
colnames(dclus1)

Description

A sample of voting data from US states or counties (depending on data availability), sampled with probability proportional to number of votes. The sample was drawn using Tille's splitting method, implemented in the "sampling" package.

Usage

data(election)

Format

election is a data frame with 4600 observations on the following 8 variables.

County

A factor specifying the state or country

TotPrecincts

Number of precincts in the state or county

PrecinctsReporting

Number of precincts supplying data

Bush

Votes for George W. Bush

Kerry

Votes for John Kerry

Nader

Votes for Ralph Nader

votes

Total votes for those three candidates

p

Sampling probability, proportional to votes

election_pps is a sample of 40 counties or states taken with probability proportional to the number of votes. It includes the additional column wt with the sampling weights.

election_insample indicates which rows of election were sampled.

election_jointprob are the pairwise sampling probabilities and election_jointHR are approximate pairwise sampling probabilities using the Hartley-Rao approximation.

Source

.

Examples

data(election)
## high positive correlation between totals
plot(Bush~Kerry,data=election,log="xy")
## high negative correlation between proportions
plot(I(Bush/votes)~I(Kerry/votes), data=election)

## Variances without replacement
## Horvitz-Thompson type
dpps_br<- svydesign(id=~1,  fpc=~p, data=election_pps, pps="brewer")
dpps_ov<- svydesign(id=~1,  fpc=~p, data=election_pps, pps="overton")
dpps_hr<- svydesign(id=~1,  fpc=~p, data=election_pps, pps=HR(sum(election$p^2)/40))
dpps_hr1<- svydesign(id=~1, fpc=~p, data=election_pps, pps=HR())
dpps_ht<- svydesign(id=~1,  fpc=~p, data=election_pps, pps=ppsmat(election_jointprob))
## Yates-Grundy type
dpps_yg<- svydesign(id=~1,  fpc=~p, data=election_pps, pps=ppsmat(election_jointprob),variance="YG")
dpps_hryg<- svydesign(id=~1,  fpc=~p, data=election_pps, pps=HR(sum(election$p^2)/40),variance="YG")

## The with-replacement approximation
dppswr <-svydesign(id=~1, probs=~p, data=election_pps)

svytotal(~Bush+Kerry+Nader, dpps_ht)
svytotal(~Bush+Kerry+Nader, dpps_yg)
svytotal(~Bush+Kerry+Nader, dpps_hr)
svytotal(~Bush+Kerry+Nader, dpps_hryg)
svytotal(~Bush+Kerry+Nader, dpps_hr1)
svytotal(~Bush+Kerry+Nader, dpps_br)
svytotal(~Bush+Kerry+Nader, dpps_ov)
svytotal(~Bush+Kerry+Nader, dppswr)

Description

Creates or adjusts a two-phase survey design object using a logistic regression model for second-phase sampling probability. This function should be particularly useful in reweighting to account for missing data.

Usage

estWeights(data,formula,...)
## S3 method for class 'twophase'
estWeights(data,formula=NULL, working.model=NULL,...)
## S3 method for class 'data.frame'
estWeights(data,formula=NULL, working.model=NULL,
      subset=NULL, strata=NULL,...)

Arguments

Details

If data is a data frame, estWeights first creates a two-phase design object. The strata argument is used only to compute finite population corrections, the same variables must be included in formula to compute stratified sampling probabilities.

With a two-phase design object, estWeights estimates the sampling probabilities using logistic regression as described by Robins et al (1994) and adds information to the object to enable correct sandwich standard errors to be computed.

An alternative to specifying formula is to specify working.model. The estimating functions from this model will be used as predictors of the sampling probabilities, which will increase efficiency to the extent that the working model and the model of interest estimate the same parameters (Kulich & Lin 2004).

The effect on a two-phase design object is very similar to calibrate, and is identical when formula specifies a saturated model.

Value

A two-phase survey design object.

References

Breslow NE, Lumley T, Ballantyne CM, Chambless LE, Kulich M. (2009) Using the Whole Cohort in the Analysis of Case-Cohort Data. Am J Epidemiol. 2009 Jun 1;169(11):1398-405.

Robins JM, Rotnitzky A, Zhao LP. (1994) Estimation of regression coefficients when some regressors are not always observed. Journal of the American Statistical Association, 89, 846-866.

Kulich M, Lin DY (2004). Improving the Efficiency of Relative-Risk Estimation in Case-Cohort Studies. Journal of the American Statistical Association, Vol. 99, pp.832-844

Lumley T, Shaw PA, Dai JY (2011) "Connections between survey calibration estimators and semiparametric models for incomplete data" International Statistical Review. 79:200-220. (with discussion 79:221-232)

See Also

postStratify, calibrate, twophase

Examples

data(airquality)

## ignoring missingness, using model-based standard error
summary(lm(log(Ozone)~Temp+Wind, data=airquality))

## Without covariates to predict missingness we get
## same point estimates, but different (sandwich) standard errors
daq<-estWeights(airquality, formula=~1,subset=~I(!is.na(Ozone)))
summary(svyglm(log(Ozone)~Temp+Wind,design=daq))

## Reweighting based on weather, month
d2aq<-estWeights(airquality, formula=~Temp+Wind+Month,
                 subset=~I(!is.na(Ozone)))
summary(svyglm(log(Ozone)~Temp+Wind,design=d2aq))

Description

The fpc data frame has 8 rows and 6 columns. It is artificial data to illustrate survey sampling estimators.

Usage

data(fpc)

Format

This data frame contains the following columns:

stratid

Stratum ids

psuid

Sampling unit ids

weight

Sampling weights

nh

number sampled per stratum

Nh

population size per stratum

x

data

Source

⁠https://www.stata-press.com/data/r7/fpc.dta⁠

Examples

data(fpc)
fpc


withoutfpc<-svydesign(weights=~weight, ids=~psuid, strata=~stratid, variables=~x, 
   data=fpc, nest=TRUE)

withoutfpc
svymean(~x, withoutfpc)

withfpc<-svydesign(weights=~weight, ids=~psuid, strata=~stratid,
fpc=~Nh, variables=~x, data=fpc, nest=TRUE)

withfpc
svymean(~x, withfpc)

## Other equivalent forms 
withfpc<-svydesign(prob=~I(1/weight), ids=~psuid, strata=~stratid,
fpc=~Nh, variables=~x, data=fpc, nest=TRUE)

svymean(~x, withfpc)

withfpc<-svydesign(weights=~weight, ids=~psuid, strata=~stratid,
fpc=~I(nh/Nh), variables=~x, data=fpc, nest=TRUE)

svymean(~x, withfpc)

withfpc<-svydesign(weights=~weight, ids=~interaction(stratid,psuid),
strata=~stratid, fpc=~I(nh/Nh), variables=~x, data=fpc)

svymean(~x, withfpc)

withfpc<-svydesign(ids=~psuid, strata=~stratid, fpc=~Nh,
 variables=~x,data=fpc,nest=TRUE)

svymean(~x, withfpc)

withfpc<-svydesign(ids=~psuid, strata=~stratid,
fpc=~I(nh/Nh), variables=~x, data=fpc, nest=TRUE)

svymean(~x, withfpc)

Description

Reformat the output of survey computations to a table.

Usage

## S3 method for class 'svystat'
ftable(x, rownames,...)
## S3 method for class 'svrepstat'
ftable(x, rownames,...)
## S3 method for class 'svyby'
ftable(x,...)

Arguments

Value

An object of class "ftable"

See Also

ftable

Examples

data(api)
dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)

a<-svymean(~interaction(stype,comp.imp), design=dclus1)
b<-ftable(a, rownames=list(stype=c("E","H","M"),comp.imp=c("No","Yes")))
b

a<-svymean(~interaction(stype,comp.imp), design=dclus1, deff=TRUE)
b<-ftable(a, rownames=list(stype=c("E","H","M"),comp.imp=c("No","Yes")))
round(100*b,1)

rclus1<-as.svrepdesign(dclus1)
a<-svytotal(~interaction(stype,comp.imp), design=rclus1)
b<-ftable(a, rownames=list(stype=c("E","H","M"),comp.imp=c("No","Yes")))
b
round(b)

a<-svyby(~api99 + api00, ~stype + sch.wide, rclus1, svymean, keep.var=TRUE)
ftable(a)
print(ftable(a),digits=2)

b<-svyby(~api99 + api00, ~stype + sch.wide, rclus1, svymean, keep.var=TRUE, deff=TRUE)
print(ftable(b),digits=2)

d<-svyby(~api99 + api00, ~stype + sch.wide, rclus1, svymean, keep.var=TRUE, vartype=c("se","cvpct"))
round(ftable(d),1)

Description

Returns a Hadamard matrix of dimension larger than the argument.

Usage

hadamard(n)

Arguments

Details

For most n the matrix comes from paley. The $36\times 36$ matrix is from Plackett and Burman (1946) and the $28\times 28$ is from Sloane's library of Hadamard matrices.

Matrices of dimension every multiple of 4 are thought to exist, but this function doesn't know about all of them, so it will sometimes return matrices that are larger than necessary. The excess is at most 4 for $n<180$ and at most 5% for $n>100$.

Value

A Hadamard matrix

Note

Strictly speaking, a Hadamard matrix has entries +1 and -1 rather than 1 and 0, so 2*hadamard(n)-1 is a Hadamard matrix

References

Sloane NJA. A Library of Hadamard Matrices http://neilsloane.com/hadamard/

Plackett RL, Burman JP. (1946) The Design of Optimum Multifactorial Experiments Biometrika, Vol. 33, No. 4 pp. 305-325

Cameron PJ (2005) Hadamard Matrices http://designtheory.org/library/encyc/topics/had.pdf. In: The Encyclopedia of Design Theory http://designtheory.org/library/encyc/

See Also

brrweights, paley

Examples

par(mfrow=c(2,2))
## Sylvester-type
image(hadamard(63),main=quote("Sylvester: "*64==2^6))
## Paley-type
image(hadamard(59),main=quote("Paley: "*60==59+1))
## from NJ Sloane's library
image(hadamard(27),main=quote("Stored: "*28))
## For n=90 we get 96 rather than the minimum possible size, 92.
image(hadamard(90),main=quote("Constructed: "*96==2^3%*%(11+1)))

par(mfrow=c(1,1))
plot(2:150,sapply(2:150,function(i) ncol(hadamard(i))),type="S",
     ylab="Matrix size",xlab="n",xlim=c(1,150),ylim=c(1,150))
abline(0,1,lty=3)
lines(2:150, 2:150-(2:150 %% 4)+4,col="purple",type="S",lty=2)
legend(c(x=10,y=140),legend=c("Actual size","Minimum possible size"),
     col=c("black","purple"),bty="n",lty=c(1,2))

Description

The hospital data frame has 15 rows and 5 columns.

Usage

data(hospital)

Format

This data frame contains the following columns:

hospno

Hospital id

oblevel

level of obstetric care

weighta

Weights, as given by the original reference

tothosp

total hospitalisations

births

births

weightats

Weights, as given in the source

Source

Previously at ⁠http://www.ats.ucla.edu/stat/books/sop/hospsamp.dta⁠

References

Levy and Lemeshow. "Sampling of Populations" (3rd edition). Wiley.

Examples

data(hospital)
hospdes<-svydesign(strata=~oblevel, id=~hospno, weights=~weighta,
fpc=~tothosp, data=hospital)
hosprep<-as.svrepdesign(hospdes)

svytotal(~births, design=hospdes)
svytotal(~births, design=hosprep)

Description

The Horvitz-Thompson estimator and the Hartley-Rao approximation require information in addition to the sampling probabilities for sampled individuals. These functions allow this information to be supplied.

Usage

HR(psum=NULL, strata = NULL)
ppsmat(jointprob, tolerance = 1e-04)
ppscov(probcov, weighted=FALSE)

Arguments

Value

An object of class HR,ppsmat, ppsdelta, or ppsdcheck suitable for supplying as the pps argument to svydesign.

See Also

election for examples of PPS designs

Examples

HR(0.1)

Description

Create calibration metric for use in calibrate. The function F is the link function described in section 2 of Deville et al. To create a new calibration metric, specify $F-1$ and its derivative. The package provides cal.linear, cal.raking, cal.logit, which are standard, and cal.sinh from the CALMAR2 macro, for which F is the derivative of the inverse hyperbolic sine.

Usage

make.calfun(Fm1, dF, name)

Arguments

Value

An object of class "calfun"

References

Deville J-C, Sarndal C-E, Sautory O (1993) Generalized Raking Procedures in Survey Sampling. JASA 88:1013-1020

Deville J-C, Sarndal C-E (1992) Calibration Estimators in Survey Sampling. JASA 87: 376-382

See Also

calibrate

Examples

str(cal.linear)
cal.linear$Fm1
cal.linear$dF

hellinger <- make.calfun(Fm1=function(u, bounds)  ((1-u/2)^-2)-1,
                    dF= function(u, bounds) (1-u/2)^-3 ,
                    name="hellinger distance")

hellinger

data(api)
dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)

svymean(~api00,calibrate(dclus1, ~api99, pop=c(6194, 3914069),
         calfun=hellinger))

svymean(~api00,calibrate(dclus1, ~api99, pop=c(6194, 3914069),
         calfun=cal.linear))

svymean(~api00,calibrate(dclus1, ~api99, pop=c(6194,3914069),
          calfun=cal.raking))

Description

Reweights the design (using calibrate) so that the adjustment variables are uncorrelated with the variables in the model, and then performs predictions by calling predict. When the adjustment model is saturated this is equivalent to direct standardization on the adjustment variables.

The svycoxph and svykmlist methods return survival curves.

Usage

marginpred(model, adjustfor, predictat, ...)
## S3 method for class 'svycoxph'
marginpred(model, adjustfor, predictat, se=FALSE, ...)
## S3 method for class 'svykmlist'
marginpred(model, adjustfor, predictat, se=FALSE, ...)
## S3 method for class 'svyglm'
marginpred(model, adjustfor, predictat,  ...)

Arguments

See Also

svypredmeans for the method of Graubard and Korn implemented in SUDAAN.

calibrate

predict.svycoxph

Examples

## generate data with apparent group effect from confounding
set.seed(42)
df<-data.frame(x=rnorm(100))
df$time<-rexp(100)*exp(df$x-1)
df$status<-1
df$group<-(df$x+rnorm(100))>0
des<-svydesign(id=~1,data=df)
newdf<-data.frame(group=c(FALSE,TRUE), x=c(0,0))

## Cox model
m0<-svycoxph(Surv(time,status)~group,design=des)
m1<-svycoxph(Surv(time,status)~group+x,design=des)
## conditional predictions, unadjusted and adjusted
cpred0<-predict(m0, type="curve", newdata=newdf, se=TRUE)
cpred1<-predict(m1, type="curve", newdata=newdf, se=TRUE)
## adjusted marginal prediction
mpred<-marginpred(m0, adjustfor=~x, predictat=newdf, se=TRUE)

plot(cpred0)
lines(cpred1[[1]],col="red")
lines(cpred1[[2]],col="red")
lines(mpred[[1]],col="blue")
lines(mpred[[2]],col="blue")

## Kaplan--Meier
s2<-svykm(Surv(time,status>0)~group, design=des)
p2<-marginpred(s2, adjustfor=~x, predictat=newdf,se=TRUE)
plot(s2)
lines(p2[[1]],col="green")
lines(p2[[2]],col="green")

## logistic regression
logisticm <- svyglm(group~time, family=quasibinomial, design=des)
newdf$time<-c(0.1,0.8)
logisticpred <- marginpred(logisticm, adjustfor=~x, predictat=newdf)

Description

The MU284 population comes from Sarndal et al, and the complete data are available from Statlib. These data are a two-stage sample from the population, analyzed on page 143 of the book.

Usage

data(mu284)

Format

A data frame with 15 observations on the following 5 variables.

id1

identifier for PSU

n1

number of PSUs in population

id2

identifier for second-stage unit

y1

variable to be analysed

n2

number of second-stage units in this PSU

Source

Carl Erik Sarndal, Bengt Swensson, Jan Wretman. (1991) "Model Assisted Survey Sampling" Springer.

(downloaded from StatLib, which is no longer active)

Examples

data(mu284)
(dmu284<-svydesign(id=~id1+id2,fpc=~n1+n2, data=mu284))
(ytotal<-svytotal(~y1, dmu284))
vcov(ytotal)

Description

Given a list of samples from K different sampling frames and information about which observations are in which frame, constructs an object representing the whole multi-frame sample. If an unit is in the overlap of multiple frames in the population it is effectively split into multiple separate units and so the weight is split if it is sampled. To optimise the split of frame weights, see reweight

Usage

multiframe(designs, overlaps, estimator = c("constant", "expected"), theta = NULL)

Arguments

Details

It is not necessary that the frame samples contain exactly the same variables or that they are in the same order, although only variables present in all the samples can be used. It is important that factor variables existing across more than one frame sample have the same factor levels in all the samples.

All these estimators assume sampling is independent between frames, and that any observation sampled more than once is present in the dataset each time it is sampled.

Value

Object of class multiframe

References

Bankier, M. D. (1986) Estimators Based on Several Stratified Samples With Applications to Multiple Frame Surveys. Journal of the American Statistical Association, Vol. 81, 1074 - 1079.

Hartley, H. O. (1962) Multiple Frames Surveys. Proceedings of the American Statistical Association, Social Statistics Sections, 203 - 206. Hartley, H. O. (1974) Multiple frame methodology and selected applications. Sankhya C, Vol. 36, 99 - 118.

Kalton, G. and Anderson, D. W. (1986) Sampling Rare Populations. Journal of the Royal Statistical Society, Ser. A, Vol. 149, 65 - 82.

See Also

svydesign, reweight

For a simple introduction: Metcalf P and Scott AJ (2009) Using multiple frames in health surveys. Stat Med 28:1512-1523

For general reference: Lohr SL, Rao JNK. Inference from dual frame surveys. Journal of the American Statistical Association 2000; 94:271-280.

Lohr SL, Rao JNK. Estimation in multiple frame surveys. Journal of the American Statistical Association 2006; 101:1019-1030.

Examples

data(phoneframes)
A_in_frames<-cbind(1, DatA$Domain=="ab")
B_in_frames<-cbind(DatB$Domain=="ba",1)

Bdes_pps<-svydesign(id=~1, fpc=~ProbB, data=DatB,pps=ppsmat(PiklB))
Ades_pps <-svydesign(id=~1, fpc=~ProbA,data=DatA,pps=ppsmat(PiklA))

## optimal constant (Hartley) weighting
mf_pps<-multiframe(list(Ades_pps,Bdes_pps),list(A_in_frames,B_in_frames),theta=0.74) 
svytotal(~Lei,mf_pps)
svymean(~Lei, mf_pps)

svyby(~Lei, ~Size, svymean, design=mf_pps)
svytable(~Size+I(Lei>20), mf_pps,round=TRUE)

Description

These objects represent designs with arbitrarily many nested phases of sampling, allowing estimation and calibration/raking at each phase

Usage

multiphase(ids, subset, strata, probs, data, fpc = NULL,
check.variable.phase=TRUE)

Arguments

Details

Variance calculation uses a decomposition with sampling contributions at each stage, which are returned as the phases attribution of a variance-covariance matrix. The computations broadly follow the description for two-phase sampling in chapter 9 of Sarndal et al (1991); there is more detail in the vignette

Value

Object of class multiphase

Note

There are currently methods for svytotal, svymean, svyglm, svyvar.

References

Sarndal, Swensson, and Wretman (1991) "Model Assisted Survey Sampling" (Chapter 9)

See Also

twophase for older implementations of two-phase sampling

vignette("multiphase") for computational details

Examples

data(nwtco)
dcchs<-twophase(id = list(~seqno, ~seqno), strata = list(NULL, ~rel), 
    subset = ~I(in.subcohort | rel), data = nwtco)
mcchs<-multiphase(id = list(~seqno, ~seqno), strata = list(NULL, ~rel), 
    subset = list(~I(in.subcohort | rel)), probs = list(~1, NULL), 
    data = nwtco)
dcchs
mcchs
svymean(~edrel, dcchs)
svymean(~edrel, mcchs)

summary(svyglm(edrel~rel+histol+stage, design=dcchs))
summary(svyglm(edrel~rel+histol+stage, design=mcchs))

m<-calibrate(mcchs,~factor(stage)+rel, phase=2, calfun="raking")
vcov(svytotal(~factor(stage), m))

Description

These data are in a paper by JNK Rao and colleagues, on score tests for complex survey data. External information (not further specified) suggests the functional form for the Age variable.

Usage

data("myco")

Format

A data frame with 516 observations on the following 6 variables.

Age

Age in years at the midpoint of six age strata

Scar

Presence of a BCG vaccination scar

n

Sampled number of cases (and thus controls) in the age stratum

Ncontrol

Number of non-cases in the population

wt

Sampling weight

leprosy

case status 0/1

Details

The data are a simulated stratified case-control study drawn from a population study conducted in a region of Malawi (Clayton and Hills, 1993, Table 18.1). The goal was to examine whether BCG vaccination against tuberculosis protects against leprosy (the causative agents are both species of _Mycobacterium_). Rao et al have a typographical error: the number of non-cases in the population in the 25-30 age stratum is given as 4981 but 5981 matches both the computational output and the data as given by Clayton and Hills.

Source

JNK Rao, AJ Scott, and Skinner, C. (1998). QUASI-SCORE TESTS WITH SURVEY DATA. Statistica Sinica, 8(4), 1059-1070.

Clayton, D., & Hills, M. (1993). Statistical Models in Epidemiology. OUP

Examples

data(myco)
dmyco<-svydesign(id=~1, strata=~interaction(Age,leprosy),weights=~wt,data=myco)

m_full<-svyglm(leprosy~I((Age+7.5)^-2)+Scar, family=quasibinomial, design=dmyco)
m_age<-svyglm(leprosy~I((Age+7.5)^-2), family=quasibinomial, design=dmyco)
anova(m_full,m_age)

## unweighted model does not match
m_full
glm(leprosy~I((Age+7.5)^-2)+Scar, family=binomial, data=myco)

Description

Estimates quantiles and confidence intervals for them. This function was completely re-written for version 4.1 of the survey package, and has a wider range of ways to define the quantile. See the vignette for a list of them.

Usage

svyquantile(x, design, quantiles, ...)
## S3 method for class 'survey.design'
svyquantile(x, design, quantiles, alpha = 0.05,
                      interval.type = c("mean", "beta","xlogit", "asin","score"),
                      na.rm = FALSE,  ci=TRUE, se = ci,
                      qrule=c("math","school","shahvaish","hf1","hf2","hf3",
		      "hf4","hf5","hf6","hf7","hf8","hf9"),
                      df = NULL, ...)
## S3 method for class 'svyrep.design'
svyquantile(x, design, quantiles, alpha = 0.05,
                      interval.type = c("mean", "beta","xlogit", "asin","quantile"),
                      na.rm = FALSE, ci = TRUE, se=ci,
                      qrule=c("math","school","shahvaish","hf1","hf2","hf3",
		      "hf4","hf5","hf6","hf7","hf8","hf9"),
                      df = NULL, return.replicates=FALSE,...)

Arguments

Details

The pth quantile is defined as the value where the estimated cumulative distribution function is equal to p. As with quantiles in unweighted data, this definition only pins down the quantile to an interval between two observations, and a rule is needed to interpolate. The default is the mathematical definition, the lower end of the quantile interval; qrule="school" uses the midpoint of the quantile interval; "hf1" to "hf9" are weighted analogues of type=1 to 9 in quantile. See the vignette "Quantile rules" for details and for how to write your own.

By default, confidence intervals are estimated using Woodruff's (1952) method, which involves computing the quantile, estimating a confidence interval for the proportion of observations below the quantile, and then transforming that interval using the estimated CDF. In that context, the interval.type argument specifies how the confidence interval for the proportion is computed, matching svyciprop. In contrast to oldsvyquantile, NaN is returned if a confidence interval endpoint on the probability scale falls outside [0,1].

There are two exceptions. For svydesign objects, interval.type="score" asks for the Francisco & Fuller confidence interval based on inverting a score test. According to Dorfmann & Valliant, this interval has inferior performance to the "beta" and "logit" intervals; it is provided for compatibility.

For replicate-weight designs, interval.type="quantile" ask for an interval based directly on the replicates of the quantile. This interval is not valid for jackknife-type replicates, though it should perform well for bootstrap-type replicates, BRR, and SDR.

The df argument specifies degrees of freedom for a t-distribution approximation to distributions of means. The default is the design degrees of freedom. Specify df=Inf to use a Normal distribution (eg, for compatibility).

When the standard error is requested, it is estimated by dividing the confidence interval length by the number of standard errors in a t confidence interval with the specified alpha. For example, with alpha=0.05 and df=Inf the standard error is estimated as the confidence interval length divided by 2*1.96.

Value

An object of class "newsvyquantile", except that with a replicate-weights design and interval.type="quantile" and return.replicates=TRUE it's an object of class "svrepstat"

References

Dorfman A, Valliant R (1993) Quantile variance estimators in complex surveys. Proceedings of the ASA Survey Research Methods Section. 1993: 866-871

Francisco CA, Fuller WA (1986) Estimation of the distribution function with a complex survey. Technical Report, Iowa State University.

Hyndman, R. J. and Fan, Y. (1996) Sample quantiles in statistical packages, The American Statistician 50, 361-365.

Shah BV, Vaish AK (2006) Confidence Intervals for Quantile Estimation from Complex Survey Data. Proceedings of the Section on Survey Research Methods.

Woodruff RS (1952) Confidence intervals for medians and other position measures. JASA 57, 622-627.

See Also

vignette("qrule", package = "survey") oldsvyquantile quantile

Examples

data(api)
## population
quantile(apipop$api00,c(.25,.5,.75))

## one-stage cluster sample
dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)
rclus1<-as.svrepdesign(dclus1)
bclus1<-as.svrepdesign(dclus1,type="boot")


svyquantile(~api00, dclus1, c(.25,.5,.75))
svyquantile(~api00, dclus1, c(.25,.5,.75),interval.type="beta")

svyquantile(~api00, rclus1, c(.25,.5,.75))
svyquantile(~api00, rclus1, c(.25,.5,.75),interval.type="quantile")
svyquantile(~api00, bclus1, c(.25,.5,.75),interval.type="quantile")

svyquantile(~api00+ell, dclus1, c(.25,.5,.75), qrule="math")
svyquantile(~api00+ell, dclus1, c(.25,.5,.75), qrule="school")
svyquantile(~api00+ell, dclus1, c(.25,.5,.75), qrule="hf8")

Description

Data extracted from NHANES 2009-2010 on high cholesterol.

Usage

data(nhanes)

Format

A data frame with 8591 observations on the following 7 variables.

SDMVPSU

Primary sampling units

SDMVSTRA

Sampling strata

WTMEC2YR

Sampling weights

HI_CHOL

Numeric vector: 1 for total cholesterol over 240mg/dl, 0 under 240mg/dl

race

1=Hispanic, 2=non-Hispanic white, 3=non-Hispanic black, 4=other

agecat

Age group (0,19] (19,39] (39,59] (59,Inf]

RIAGENDR

Gender: 1=male, 2=female

Source

Previously at ⁠https://wwwn.cdc.gov/nchs/nhanes/search/datapage.aspx?Component=laboratory&CycleBeginYear=2009⁠

Examples

data(nhanes)
design <- svydesign(id=~SDMVPSU, strata=~SDMVSTRA, weights=~WTMEC2YR, nest=TRUE,data=nhanes)
design

Description

Functions to simplify the construction of non-reponse weights by combining strata with small numbers or large weights.

Usage

nonresponse(sample.weights, sample.counts, population)
sparseCells(object, count=0,totalweight=Inf, nrweight=1.5)
neighbours(index,object)
joinCells(object,a,...)
## S3 method for class 'nonresponse'
weights(object,...)

Arguments

Details

When a stratified survey is conducted with imperfect response it is desirable to rescale the sampling weights to reflect the nonresponse. If some strata have small sample size, high non-response, or already had high sampling weights it may be desirable to get less variable non-response weights by averaging non-response across strata. Suitable strata to collapse may be similar on the stratifying variables and/or on the level of non-response.

nonresponse() combines stratified tables of population size, sample size, and sample weight into an object. sparseCells identifies cells that may need combining. neighbours describes the cells adjacent to a specified cell, and joinCells collapses the specified cells. When the collapsing is complete, use weights() to extract the nonresponse weights.

Value

nonresponse and joinCells return objects of class "nonresponse", neighbours and sparseCells return objects of class "nonresponseSubset"

Examples

data(api)
## pretend the sampling was stratified on three variables
poptable<-xtabs(~sch.wide+comp.imp+stype,data=apipop)
sample.count<-xtabs(~sch.wide+comp.imp+stype,data=apiclus1)
sample.weight<-xtabs(pw~sch.wide+comp.imp+stype, data=apiclus1)

## create a nonresponse object
nr<-nonresponse(sample.weight,sample.count, poptable)

## sparse cells
sparseCells(nr)

## Look at neighbours
neighbours(3,nr)
neighbours(11,nr)

## Collapse some contiguous cells
nr1<-joinCells(nr,3,5,7)

## sparse cells now
sparseCells(nr1)
nr2<-joinCells(nr1,3,11,8)

nr2

## one relatively sparse cell
sparseCells(nr2)
## but nothing suitable to join it to
neighbours(3,nr2)

## extract the weights
weights(nr2)

Description

Compute quantiles for data from complex surveys. oldsvyquantile is the version of the function from before version 4.1 of the package, available for backwards compatibility. See svyquantile for the current version

Usage

## S3 method for class 'survey.design'
oldsvyquantile(x, design, quantiles, alpha=0.05,
   ci=FALSE, method = "linear", f = 1,
   interval.type=c("Wald","score","betaWald"), na.rm=FALSE,se=ci,
   ties=c("discrete","rounded"), df=NULL,...)
## S3 method for class 'svyrep.design'
oldsvyquantile(x, design, quantiles,
   method ="linear", interval.type=c("probability","quantile"), f = 1,
   return.replicates=FALSE, ties=c("discrete","rounded"),na.rm=FALSE,
   alpha=0.05,df=NULL,...)

Arguments

Details

The definition of the CDF and thus of the quantiles is ambiguous in the presence of ties. With ties="discrete" the data are treated as genuinely discrete, so the CDF has vertical steps at tied observations. With ties="rounded" all the weights for tied observations are summed and the CDF interpolates linearly between distinct observed values, and so is a continuous function. Combining interval.type="betaWald" and ties="discrete" is (close to) the proposal of Shah and Vaish(2006) used in some versions of SUDAAN.

Interval estimation for quantiles is complicated, because the influence function is not continuous. Linearisation cannot be used directly, and computing the variance of replicates is valid only for some designs (eg BRR, but not jackknife). The interval.type option controls how the intervals are computed.

For survey.design objects the default is interval.type="Wald". A 95% Wald confidence interval is constructed for the proportion below the estimated quantile. The inverse of the estimated CDF is used to map this to a confidence interval for the quantile. This is the method of Woodruff (1952). For "betaWald" the same procedure is used, but the confidence interval for the proportion is computed using the exact binomial cdf with an effective sample size proposed by Korn & Graubard (1998).

If interval.type="score" we use a method described by Binder (1991) and due originally to Francisco and Fuller (1986), which corresponds to inverting a robust score test. At the upper and lower limits of the confidence interval, a test of the null hypothesis that the cumulative distribution function is equal to the target quantile just rejects. This was the default before version 2.9. It is much slower than "Wald", and Dorfman & Valliant (1993) suggest it is not any more accurate.

Standard errors are computed from these confidence intervals by dividing the confidence interval length by 2*qnorm(alpha/2).

For replicate-weight designs, ordinary replication-based standard errors are valid for BRR and Fay's method, and for some bootstrap-based designs, but not for jackknife-based designs. interval.type="quantile" gives these replication-based standard errors. The default, interval.type="probability" computes confidence on the probability scale and then transforms back to quantiles, the equivalent of interval.type="Wald" for survey.design objects (with alpha=0.05).

There is a confint method for svyquantile objects; it simply extracts the pre-computed confidence interval.

Value

returns a list whose first component is the quantiles and second component is the confidence intervals. For replicate weight designs, returns an object of class svyrepstat.

Author(s)

Thomas Lumley

References

Binder DA (1991) Use of estimating functions for interval estimation from complex surveys. Proceedings of the ASA Survey Research Methods Section 1991: 34-42

Dorfman A, Valliant R (1993) Quantile variance estimators in complex surveys. Proceedings of the ASA Survey Research Methods Section. 1993: 866-871

Korn EL, Graubard BI. (1998) Confidence Intervals For Proportions With Small Expected Number of Positive Counts Estimated From Survey Data. Survey Methodology 23:193-201.

Francisco CA, Fuller WA (1986) Estimation of the distribution function with a complex survey. Technical Report, Iowa State University.

Shao J, Tu D (1995) The Jackknife and Bootstrap. Springer.

Shah BV, Vaish AK (2006) Confidence Intervals for Quantile Estimation from Complex Survey Data. Proceedings of the Section on Survey Research Methods.

Woodruff RS (1952) Confidence intervals for medians and other position measures. JASA 57, 622-627.

See Also

svykm for quantiles of survival curves

svyciprop for confidence intervals on proportions.

Examples

data(api)
  ## population
  quantile(apipop$api00,c(.25,.5,.75))

  ## one-stage cluster sample
  dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)
  oldsvyquantile(~api00, dclus1, c(.25,.5,.75),ci=TRUE)
  oldsvyquantile(~api00, dclus1, c(.25,.5,.75),ci=TRUE,interval.type="betaWald")
  oldsvyquantile(~api00, dclus1, c(.25,.5,.75),ci=TRUE,df=NULL)

  dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)
  (qapi<-oldsvyquantile(~api00, dclus1, c(.25,.5,.75),ci=TRUE, interval.type="score"))
  SE(qapi)

  #stratified sample
  dstrat<-svydesign(id=~1, strata=~stype, weights=~pw, data=apistrat, fpc=~fpc)
  oldsvyquantile(~api00, dstrat, c(.25,.5,.75),ci=TRUE)

  #stratified sample, replicate weights
  # interval="probability" is necessary for jackknife weights
  rstrat<-as.svrepdesign(dstrat)
  oldsvyquantile(~api00, rstrat, c(.25,.5,.75), interval.type="probability")


  # BRR method
  data(scd)
  repweights<-2*cbind(c(1,0,1,0,1,0), c(1,0,0,1,0,1), c(0,1,1,0,0,1),
              c(0,1,0,1,1,0))
  scdrep<-svrepdesign(data=scd, type="BRR", repweights=repweights)
  oldsvyquantile(~arrests+alive, design=scdrep, quantile=0.5, interval.type="quantile")
  oldsvyquantile(~arrests+alive, design=scdrep, quantile=0.5, interval.type="quantile",df=NULL)

Description

A database-backed survey design object contains a connection to a database. This connection will be broken if the object is saved and reloaded, and the connection should ideally be closed with close before quitting R (although it doesn't matter for SQLite connections). The connection can be reopened with open.

Usage

## S3 method for class 'DBIsvydesign'
open(con, ...)
## S3 method for class 'DBIsvydesign'
close(con, ...)

Arguments

Value

The same survey design object with the connection opened or closed.

See Also

svydesign

DBI package

Examples

## Not run: 
library(RSQLite)
dbclus1<-svydesign(id=~dnum, weights=~pw, fpc=~fpc,
data="apiclus1",dbtype="SQLite",
dbname=system.file("api.db",package="survey"))

dbclus1
close(dbclus1)
dbclus1
try(svymean(~api00, dbclus1))

dbclus1<-open(dbclus1)
open(dbclus1)
svymean(~api00, dbclus1)

## End(Not run)

Description

Computes a Hadamard matrix of dimension $(p+1)\times 2^k$, where p is a prime, and p+1 is a multiple of 4, using the Paley construction. Used by hadamard.

Usage

paley(n, nmax = 2 * n, prime=NULL, check=!is.null(prime))

is.hadamard(H, style=c("0/1","+-"), full.orthogonal.balance=TRUE)

Arguments

Details

The Paley construction gives a Hadamard matrix of order p+1 if p is prime and p+1 is a multiple of 4. This is then expanded to order $(p+1)\times 2^k$ using the Sylvester construction.

paley knows primes up to 7919. The user can specify a prime with the prime argument, in which case a matrix of order $p+1$ is constructed.

If check=TRUE the code uses is.hadamard to check that the resulting matrix really is of Hadamard type, in the same way as in the example below. As this test takes $n^3$ time it is preferable to just be sure that prime really is prime.

A Hadamard matrix including a row of 1s gives BRR designs where the average of the replicates for a linear statistic is exactly the full sample estimate. This property is called full orthogonal balance.

Value

For paley, a matrix of zeros and ones, or NULL if no matrix smaller than nmax can be found.

For is.hadamard, TRUE if H is a Hadamard matrix.

References

Cameron PJ (2005) Hadamard Matrices. In: The Encyclopedia of Design Theory

See Also

hadamard

Examples

M<-paley(11)

is.hadamard(M)
## internals of is.hadamard(M)
H<-2*M-1
## HH^T is diagonal for any Hadamard matrix
H%*%t(H)

Description

The distribution of a quadratic form in p standard Normal variables is a linear combination of p chi-squared distributions with 1df. When there is uncertainty about the variance, a reasonable model for the distribution is a linear combination of F distributions with the same denominator.

Usage

pchisqsum(x, df, a, lower.tail = TRUE, 
   method = c("satterthwaite", "integration","saddlepoint"))
pFsum(x, df, a, ddf=Inf,lower.tail = TRUE, 
   method = c("saddlepoint","integration","satterthwaite"), ...)

Arguments

Details

The "satterthwaite" method uses Satterthwaite's approximation, and this is also used as a fallback for the other methods. The accuracy is usually good, but is more variable depending on a than the other methods and is anticonservative in the right tail (eg for upper tail probabilities less than 10^-5). The Satterthwaite approximation requires all a>0.

"integration" requires the CompQuadForm package. For pchisqsum it uses Farebrother's algorithm if all a>0. For pFsum or when some a<0 it inverts the characteristic function using the algorithm of Davies (1980). These algorithms are highly accurate for the lower tail probability, but they obtain the upper tail probability by subtraction from 1 and so fail completely when the upper tail probability is comparable to machine epsilon or smaller.

If the CompQuadForm package is not present, a warning is given and the saddlepoint approximation is used.

"saddlepoint" uses Kuonen's saddlepoint approximation. This is moderately accurate even very far out in the upper tail or with some a=0 and does not require any additional packages. The relative error in the right tail is uniformly bounded for all x and decreases as p increases. This method is implemented in pure R and so is slower than the "integration" method.

The distribution in pFsum is standardised so that a likelihood ratio test can use the same x value as in pchisqsum. That is, the linear combination of chi-squareds is multiplied by ddf and then divided by an independent chi-squared with ddf degrees of freedom.

Value

Vector of cumulative probabilities

References

Chen, T., & Lumley T. (2019). Numerical evaluation of methods approximating the distribution of a large quadratic form in normal variables. Computational Statistics and Data Analysis, 139, 75-81.

Davies RB (1973). "Numerical inversion of a characteristic function" Biometrika 60:415-7

Davies RB (1980) "Algorithm AS 155: The Distribution of a Linear Combination of chi-squared Random Variables" Applied Statistics,Vol. 29, No. 3 (1980), pp. 323-333

P. Duchesne, P. Lafaye de Micheaux (2010) "Computing the distribution of quadratic forms: Further comparisons between the Liu-Tang-Zhang approximation and exact methods", Computational Statistics and Data Analysis, Volume 54, (2010), 858-862

Farebrother R.W. (1984) "Algorithm AS 204: The distribution of a Positive Linear Combination of chi-squared random variables". Applied Statistics Vol. 33, No. 3 (1984), p. 332-339

Kuonen D (1999) Saddlepoint Approximations for Distributions of Quadratic Forms in Normal Variables. Biometrika, Vol. 86, No. 4 (Dec., 1999), pp. 929-935

See Also

pchisq

Examples

x <- 2.7*rnorm(1001)^2+rnorm(1001)^2+0.3*rnorm(1001)^2
x.thin<-sort(x)[1+(0:50)*20]
p.invert<-pchisqsum(x.thin,df=c(1,1,1),a=c(2.7,1,.3),method="int" ,lower=FALSE)
p.satt<-pchisqsum(x.thin,df=c(1,1,1),a=c(2.7,1,.3),method="satt",lower=FALSE)
p.sadd<-pchisqsum(x.thin,df=c(1,1,1),a=c(2.7,1,.3),method="sad",lower=FALSE)

plot(p.invert, p.satt,type="l",log="xy")
abline(0,1,lty=2,col="purple")
plot(p.invert, p.sadd,type="l",log="xy")
abline(0,1,lty=2,col="purple")

pchisqsum(20, df=c(1,1,1),a=c(2.7,1,.3), lower.tail=FALSE,method="sad")
pFsum(20, df=c(1,1,1),a=c(2.7,1,.3), ddf=49,lower.tail=FALSE,method="sad")
pFsum(20, df=c(1,1,1),a=c(2.7,1,.3), ddf=1000,lower.tail=FALSE,method="sad")

Description

This dataset contains some variables regarding household expenses for a sample of 105 households selected from a list of landline phones (frame A) and a sample of 135 from a list of mobile phones (frame B) in a particular city in a specific month. These data are taken from the Frames2 package under the GPL-2 or GPL-3 licence.

Usage

data(phoneframes)

Format

Domain

A factor indicating the domain each household belongs to. In sample A, possible values are "a" if household belongs to domain a or "ab" if household belongs to overlap domain; in sample B, the values are "b" or "ba"

Feed

Feeding expenses (in euros) at the househould

Clo

Clothing expenses (in euros) at the household

Lei

Leisure expenses (in euros) at the household

Inc

Household income (in euros). Values for this variable are only available for households included in frame A. For households included in domain b, value of this variable is missing

Tax

Household municipal taxes (in euros) paid. Values for this variable are only available for households included in frame A. For households included in domain b, value of this variable is missing

M2

Square meters of the house. Values for this variable are only available for households included in frame B. For households included in domain a, value of this variable is missing

Size

Household size. Values for this variable are only available for households included in frame B. For households included in domain a, value of this variable is missing

ProbA

First order inclusion probability in frame A. This probability is 0 for households included in domain b.

ProbB

First order inclusion probability in frame B. This probability is 0 for households included in domain a.

Stratum

A numeric value indicating the stratum each household belongs to.

Details

The frame A sample, of size $n_A = 105$, has been drawn from a population of $N_A = 1735$ households with landline phone according to a stratified random sampling. Population units were divided in 6 different strata. Population sizes of these strata are $N_A^h = (727, 375, 113, 186, 115, 219)$. $N_{ab} = 601$ of the households composing the population have, also, mobile phone. On the other hand, frame totals for auxiliary variables in this frame are $X_{Income}^A = 4300260$ and $X_{Taxes}^A = 215577$.

The frame B sample, of size $n_B = 135$, has been drawn from a population of $N_B = 1191$ households with mobile phone according to a simple random sampling without replacement design. $N_{ab} = 601$ of these households have, also, landline phone. On the other hand, frame totals for auxiliary variables in this frame are $X_{Metres2}^B = 176553$ and $X_{Size}^B = 3529$

PiklA and PiklB are matrices of pairwise sampling probabilities for the two frames.

See Also

multiframe, reweight

Original package: https://CRAN.R-project.org/package=Frames2

Examples

data(phoneframes)
A_in_frames<-cbind(1, DatA$Domain=="ab")
B_in_frames<-cbind(DatB$Domain=="ba",1)

Bdes_pps<-svydesign(id=~1, fpc=~ProbB, data=DatB,pps=ppsmat(PiklB))
Ades_pps <-svydesign(id=~1, fpc=~ProbA,data=DatA,pps=ppsmat(PiklA))

## optimal constant (Hartley) weighting
mf_pps<-multiframe(list(Ades_pps,Bdes_pps),list(A_in_frames,B_in_frames),theta=0.74) 
svytotal(~Lei,mf_pps)

Awts<-cbind(1/DatA$ProbA, ifelse(DatA$ProbB==0,0,1/DatA$ProbB))
Bwts<-cbind(ifelse(DatB$ProbA==0,0,1/DatB$ProbA),1/DatB$ProbB )
## dividing by the expected number of selections (BKA or HH estimator)
mf_pps2<-multiframe(list(Ades_pps,Bdes_pps),list(Awts,Bwts),estimator="expected") 
svymean(~Lei,mf_pps2)

## Metcalf and Scott approximation
DatB$Stratum<-10
DatB$Frame<-2
DatA$Frame<-1
Dat_both<-rbind(DatA,DatB)
frame_weights<-c(0.742,1-0.742)
Dat_both$fweights<-with(Dat_both, ifelse(Frame==1, 
   ifelse(Domain=="ab", frame_weights[1]*1/ProbA,1/ProbA),
   ifelse(Domain=="ba", frame_weights[2]*1/ProbB, 1/ProbB)))

MSdesign<-svydesign(id=~1, strata=~Stratum, weights=~fweights,data=Dat_both)
svymean(~Lei,MSdesign)