Aggregating with the median

*SPSS AnswerNet solution ID:100006782 
* How to aggregate the median.

DATA LIST FREE /id score. 
BEGIN DATA 
1 1 1 2 1 3 1 4 1 5 
2 1 2 3 2 5 2 7 2 9 
3 2 3 4 3 6 3 8 3 10 
END DATA. 
** Next we aggregate the file, breaking on the id variable. 
AGGREGATE OUTFILE 'aggmedian.sav'/ 
PRESORTED/ BREAK=id/ nscore=N(score). 
** We then add this aggregated outfile back to the original 
** data file, interlacing the agreggated cases (1 per id) 
** among their associated id subgroups, and creating a new 
** variable (aggfile) to flag the cases coming from this 
** aggregated file. 
ADD FILES FILE 'aggmedian.sav'/IN=aggfile/FILE */BY id. 
exe. 
** Next we split the file by id, so that our next procedure 
** is repeated for each id group. 
SPLIT FILE BY id. 
** At this point, we know that "score" is missing for (at 
** least) one case within each split file group; we've put this case 
** there with the aggregation and re-merging of the file. We can now 
** use the RMV procedure to substitute for that missing value 
** the median across the remaining values for "score" (within 
** each id subgroup, since SPLIT FILE is in effect). 
RMV medscore=MEDIAN(score, ALL). 
** Only the flagged, "aggfile" cases hold the median values at 
** this point; we still need to substitute the subgroup medians 
** in "medscore" for each case within each id subgroup. 
IF id=LAG(id) medscore=LAG(medscore). 
EXE. 
** There's no need to retain the cases that were generated 
** by the AGGREGATE and ADD FILES and used solely to hold the 
** id subgroup medians. We can select everything but them for 
** the active file. 
SELECT IF NOT(aggfile). 
EXE. 
** At this stage, each case in the file has a value for the 
** "medscore" variable appropriate to its id subgroup. If this 
** is sufficient, you can drop the "nscore" and "aggfile" 
** variables the next time the file is saved. If your original 
** aim was indeed an aggregated file with one case per id and 
** the median within id subgroups on "score," you now have 
** everything you need for this. Several of the AGGREGATE 
** functions will capture the "medscore" values, which are 
** effectively constants within each break group. 
AGGREGATE OUTFILE */BREAK=id/aggmed=MAX(medscore).