I think you should first use AGGREGATE to compute the median SECONDS (percentile 50) for all 9 categories. Then use the resulting values to create the SPEED variable in the original file with IF commands.

Hector Maletta Universidad del Salvador Buenos Aires, Argentina

Stefano Perlusz wrote: > > Dear members, > > I've a problem to solve about COMPUTE into a new variabe, and I'm not able > to solve it by myself. > > I have 2 variables: > - CATEGORY is nominal (1 to 9), it represents the category or type of > respondent. So, it creates 9 groups in my sample. > - SECONDS is continuos (>0), represents the time spent to solve a test. > > I want to create a dummy variable: > - SPEED: it should take 0 for slow respondents and 1 for fast respondents. > Slow respondents are defined as, for each CATEGORY, the first half of > the respective group (that is, the 50% slower respondents for that group). > Fast respondents are the others. > > What would be the syntax command? > > Any help is very much appreciated! > > Stefano Perlusz