Sampling Designs - Sampling Spatial Units for Agricultural Surveys - page 122

Fig. 6.4 Sample selected with a stratified design with four strata
11 12 21 22
258 256 248 238
> set.seed(200694)
> str < - strata(framepop,"strataid",size ¼ rep(25,4),method ¼ "srswor")
> str < - getdata(framepop,str)
> smpstr < - table(str$strataid)
> smpstr
11 12 21 22
25 25 25 25
> par(mar ¼ c(1,1,1,1), xaxs ¼ "i",yaxs ¼ "i")
> plot(framepop$xc,framepop$yc, axes ¼ F,cex ¼ 0.5,
+ pch ¼ 19,xlim ¼ c(0,1),ylim ¼ c(0,1))
> abline(h ¼ 0.5,lty ¼ 2,lwd ¼ 2)
> abline(v ¼ 0.5,lty ¼ 2,lwd ¼ 2)
> box()
> points(str$xc,str$yc, pch ¼ 1, cex ¼ 2)
> dstrsrs < - svydesign(id ¼ ~1,strata ¼ ~strataid,data ¼ str,fpc ¼ ~Prob)
> estrsrs < - svytotal(~yobs+as.factor(q1obs),dstrsrs,deff ¼ T)