Getting repeated sampling from same file

SPSS AnswerNet: Result 

Solution ID:	 	100008330	
Product:	 	SPSS Base 	
Version:	 		
O/S:	 		
Question Type:	 	Syntax/Batch/Scripting	
Question Subtype:	 	Macro Facility	
Title:
Getting repeated subsamples from a dataset 
Description:
Q. 
I would like to get a subsample of cases so that I can 
get the mean of that subsample. I would like to this 
repeatedly so that I get the means of a number of subsamples. 
This way, I can prove the central tendency theorem. Is 
there a way that I can do this? 
A. 
Yes, there is. By using a macro, you can repeatedly pull 
a subsample of cases and get the mean of that subsample. 
Below is an example of how this can be done. Using the 
COUNTRY.SAV file that is found in the Norusis "SPSS Guide 
to Data Analysis" manual, we pull 30 samples of 10 cases 
each, and we get the mean and standard deviation of the GDP 
variable for those samples. 
DEFINE repsamp (). 
!DO !doover = 1 !TO 30. 
USE ALL. 
do if $casenum = 1. 
compute #s_$_1=10. 
compute #s_$_2=122. 
end if. 
do if #s_$_2 > 0. 
compute filter_$ = uniform(1)* #s_$_2 < #s_$_1. 
compute #s_$_1 = #s_$_1 - filter_$. 
compute #s_$_2 = #s_$_2 - 1. 
else. 
compute filter_$ = 0. 
end if. 
VARIABLE LABEL filter_$ '10 from the first 122 cases (SAMPLE)'. 
FORMAT filter_$ (f1.0). 
FILTER BY filter_$. 
DESCRIPTIVES 
VARIABLES=gdp 
/STATISTICS=MEAN STDDEV . 
!DOEND. 
!ENDDEFINE. 
repsamp.