svycontrast: Linear and nonlinearconstrasts of survey statistics

Description

Computes linear or nonlinear contrasts of estimates produced by survey functions (or any object with coef and vcov methods).

Usage

svycontrast(stat, contrasts, ...)

Arguments

stat

object of class svrepstat or svystat

contrasts

A vector or list of vectors of coefficients, or a call or list of calls

…

For future expansion

Value

Object of class svrepstat or svystat

Details

If contrasts is a list, the element names are used as names for the returned statistics.

If an element of contrasts is shorter than coef(stat) and has names, the names are used to match up the vectors and the remaining elements of contrasts are assumed to be zero. If the names are not legal variable names (eg 0.1) they must be quoted (eg "0.1")

If contrasts is a "call" or list of "call"s, the delta-method is used to compute variances, and the calls must use only functions that deriv knows how to differentiate. If the names are not legal variable names they must be quoted with backticks (eg `0.1`).

Examples

Run this code

# NOT RUN {
data(api)
dclus1<-svydesign(id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)

a <- svytotal(~api00+enroll+api99, dclus1)
svycontrast(a, list(avg=c(0.5,0,0.5), diff=c(1,0,-1)))
## if contrast vectors have names, zeroes may be omitted
svycontrast(a, list(avg=c(api00=0.5,api99=0.5), diff=c(api00=1,api99=-1)))

## nonlinear contrasts
svycontrast(a, quote(api00/api99))
svyratio(~api00, ~api99, dclus1)

## Example: standardised skewness coefficient
moments<-svymean(~I(api00^3)+I(api00^2)+I(api00), dclus1)
svycontrast(moments, 
quote((`I(api00^3)`-3*`I(api00^2)`*`I(api00)`+ 3*`I(api00)`*`I(api00)`^2-`I(api00)`^3)/
      (`I(api00^2)`-`I(api00)`^2)^1.5))

## Example: geometric means

meanlogs <- svymean(~log(api00)+log(api99), dclus1)
svycontrast(meanlogs,
    list(api00=quote(exp(`log(api00)`)), api99=quote(exp(`log(api99)`))))

# }