On Feb 23, 2012, at 10:49 AM, Hed Bar-Nissan wrote:
The need comes from the PISA data. (http://www.pisa.oecd.org)
In the data there are many cases and each of them carries a numeric
variable that signifies it's weight.
In SPSS the command would be "WEIGHT BY"
In simpler words here is an R sample ( What is get VS what i want
to get )
data.recieved <- data.frame(
+ kindergarten_attendance = factor(c(2,1,1,1), labels = c("Yes",
"No")),
+ weight=c(10, 1, 1, 1)
+ );
data.recieved;
kindergarten_attendance weight
1 No 10
2 Yes 1
3 Yes 1
4 Yes 1
data.weighted <- data.frame(
+ kindergarten_attendance = factor(c(2,2,2,2,2,2,2,2,2,2,1,1,1),
labels =
c("Yes", "No")) );
You want "case repetition" not case weighting, which I would use as a
term when working on estimation problems:
> ( data.weighted <- unlist(sapply(1:NROW(data.recieved),
function(x) rep(data.recieved[x,1], times=data.recieved[x,2] )) ) )
[1] No No No No No No No No No No Yes Yes Yes
Levels: Yes No
par(mfrow=c(1,2));
plot(data.recieved$kindergarten_attendance,main="What i get");
plot(data.weighted$kindergarten_attendance,main="What i want to
get");
Seems to work with the factor vector, although I didn't replicate
dataframe rows, but I guess you could.
tnx in advance
Hed
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