School Sampling

Yes, but it doesn't work when schools are sampled more than once. For example:

z<-data.frame(school=factor(rep(1:5, each=2)), score=21:30)
school.sample<-sample(levels(z$school), 3, replace=T)
school.sample

[1] "5" "5" "4"

new<-subset(z, school%in%school.sample)
new

school score
7       4    27
8       4    28
9       5    29
10      5    30

*********************************************************
Dr. J. Kyle Roberts
Department of Teaching and Learning
Annette Caldwell Simmons School of Education 
   and Human Development
Southern Methodist University
P.O. Box 750381
Dallas, TX? 75275
214-768-4494
http://www.hlm-online.com/
*********************************************************


-----Original Message-----
From: Daniel Ezra Johnson [mailto:danielezrajohnson at gmail.com] 
Sent: Wednesday, January 14, 2009 12:00 PM
To: Roberts, Kyle
Cc: r-sig-mixed-models at r-project.org
Subject: Re: [R-sig-ME] School Sampling

z<-data.frame(school=factor(rep(1:5, each=2)), score=21:30)
school.sample<-sample(levels(z$school), 3, replace=T)
school.sample

[1] "5" "1" "2"

new<-subset(z, school==school.sample)

Warning messages:
1: In is.na(e1) | is.na(e2) :
 longer object length is not a multiple of shorter object length
2: In `==.default`(school, school.sample) :
 longer object length is not a multiple of shorter object length

is it

new <- subset(z,school%in%school.sample)

that gives you the result you want?