Hi there,
I would like to use a formula inside a call to withReplicates in a survey
analysis.
If the initial call with formula expressed inside the function works as
expected, defining the formula outside gives an error message.
See example below, adapted from survey:withReplicates help page.
library(survey)
library(quantreg)
data(api)
## one-stage cluster sample
dclus1<-svydesign( id=~dnum, weights=~pw, data=apiclus1, fpc=~fpc)
## convert to bootstrap
bclus1<-as.svrepdesign( dclus1, type="bootstrap", replicates=100)
## median regression
withReplicates( bclus1, quote( coef( rq( api00~api99, tau=0.5,
weights=.weights))))
theta SE
(Intercept) 87.78505 18.850
api99 0.91589 0.028
# Defining formula outside
Myformula <- as.formula( " api00~api99")
# Rerun the same analysis
withReplicates( bclus1, quote( coef( rq( formula= Myformula, tau=0.5,
weights=.weights))))
Erreur dans eval(expr, envir, enclos) : objet 'api00' introuvable
# I suspect the evaluation not done in the right environment.
#If you specify with data option in rq, the initial dataframe, formula is then
correctly evaluated but .weights are not found.
withReplicates( bclus1, quote( coef( rq( formula= Myformula, tau=0.5,
weights=.weights, data=apiclus1 ))))
Erreur dans eval(expr, envir, enclos) : objet '.weights' introuvable
Any help greatly appreciated
O__ ---- Alain Le Tertre
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