On Feb 17, 2010, at 8:26 AM, Ista Zahn wrote:
Hi all,
I am designing a study in which I am selecting a subset of college
courses to be randomly assigned to one of two conditions. I would like
to create matched pairs of courses, and then randomly assign them to
condition within each pair. I would like to identify, for each course,
the one that best matches it, and quantify how well it matches. Here
is a much simpler data set for purposes of illustration:
ED <- data.frame(course = letters[1:5], level=factor(c(100, 100, 200,
300, 200)), size = c(44, 12, 23, 124, 30), rating = c(4,5,5,3,5))
course level size rating
1 a 100 44 4
2 b 100 12 5
3 c 200 23 5
4 d 300 124 3
5 e 200 30 5
> ED$grps <- paste(ED$level, cut(ED$size,
breaks=c(0,15,35,60,150,300)),
+ cut(ED$rating, breaks=c(0,2,4,6)), sep=".")
> ED[order(ED$grps), ]
course level size rating cuts
2 b 100 12 5 100.(0,15].(4,6]
1 a 100 44 4 100.(35,60].(2,4]
3 c 200 23 5 200.(15,35].(4,6]
5 e 200 30 5 200.(15,35].(4,6]
4 d 300 124 3 300.(60,150].(2,4]
Basically I want a function that tells me that courses c and e "match"
so that I can treat them as a pair and randomly assign them to
condition. I've looked at the matching and MatchIt packages, but they
seem to need to know in advance which course is in the treatment
condition and which is in the control condition. I'll be grateful for
any suggestions.
Best,
--
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
