Case weighting

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Hed Bar-Nissan
Sent: Thursday, February 23, 2012 12:27 PM
To: David Winsemius
Cc: r-help at r-project.org
Subject: Re: [R] Case weighting

It's really weighting - it's just that my simplified example was too
simplified
Here is my real weight vector:

sc$W_FSCHWT

  [1]  14.8579  61.9528   3.0420   2.9929   5.1239  14.7507   2.7535
2.2693   3.6658   8.6179   2.5926   2.5390   1.7354   2.9767   9.0477
2.6589   3.4040   3.0519
....


And still it should somehow set the case weight.
I could multiply all by 10000 and use maybe your method but it would
create
such a bloated dataframe

working with numeric only i could probably create weighted means

But something simple as WEIGHTED BY would be nice.

tnx
Hed





On Thu, Feb 23, 2012 at 7:43 PM, David Winsemius
<dwinsemius at comcast.net>wrote:

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.