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| From | Chris Yang <bhpchg@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: Aggregate different parts of data selectively |
| Date | Mon, 3 Feb 2014 15:39:58 -0500 |
Thank you Nick. The example is just made-up data to illustrate the structure. On Mon, Feb 3, 2014 at 2:33 PM, Nick Cox <njcoxstata@gmail.com> wrote: > Your example is rather mysterious but you could > > keep if (group == 1 & no > 2) | (group == 2 & no > 5) | (group == 3 & no > 3) > > after which -collapse- would work on all specified observations. > > Nick > njcoxstata@gmail.com > > > On 3 February 2014 19:24, Chris Yang <bhpchg@gmail.com> wrote: >> Dear All, >> >> I have a dataset of the following structure: >> >> group no var1 var2 var3 >> 1 1 3 2 1 >> 1 2 2 0 0 >> 1 3 3 0 1 >> 1 4 0 1 1 >> 1 5 1 1 2 >> ... >> 2 1 3 2 1 >> 2 2 3 0 0 >> 2 3 1 1 1 >> 2 4 0 2 1 >> 2 5 0 0 2 >> ... >> 3 1 1 1 1 >> 3 2 2 3 1 >> 3 3 2 1 1 >> ... >> >> I want to aggregate a subset of observations by group, e.g. aggregate >> (using the mean) all the observations with `no` > 2 in group 1, >> aggregate observations with `no` > 5 in group 2, aggregate >> observations with `no` > 3 in group 3, and so on. And carry out >> analysis using the aggregated data of different groups only. >> >> I know that --collapse-- can do the averaging job within each group, >> however, it will also replace all existing data with the aggregated >> data. In my case, it would mean that I lose the data for all the other >> groups once I collapse/aggregate for any single group. >> >> A tedious way is to collapse and save respective groups individually, >> and then merge the aggregated per-group data in the end. I wonder if >> there is a more efficient way to achieve my goal here? >> >> Your thoughts and suggestions are appreciated. Thanks. >> >> Best regards, >> >> Chris >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/faqs/resources/statalist-faq/ >> * http://www.ats.ucla.edu/stat/stata/ > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/