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| From | Ken Ning <kenscholar2008@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: how do you subtract the value of one group from the value of another group? |
| Date | Mon, 19 Aug 2013 22:44:08 +0100 |
Hi Nick, Thanks a lot for getting back to me. In fact, i have an unbalanced panel data and I calculate a value for each year in each group. I want the same group (e.g. group 1) in year 2 (e.g 2002) to have the value of the year 1 (2001) subtracted from it within the same group (i.e. 9-7, and 6-9) and repeat the same process for group 2 (12-11, 11-10 etc) group year value 1 2001 7 1 2001 7 1 2001 7 1 2001 7 1 2002 9 1 2002 9 1 2002 9 1 2002 9 1 2003 6 1 2003 6 1 2003 6 1 2003 6 2 2001 10 2 2001 10 2 2001 10 2 2002 11 2 2002 11 2 2002 11 2 2003 12 2 2003 12 2 2003 12 Many thanks Ken On 19 August 2013 21:36, Nick Cox <njcoxstata@gmail.com> wrote: > That wasn't my suggestion, which was geared to your example with just 2 groups. > > Now you tell us you have many groups. You need to tell us how > differences are defined. > > Your code looks _legal_, so I don't understand the error message. > > If people don't state the real problem, poor solutions are all too likely. > > Nick > njcoxstata@gmail.com > > > On 19 August 2013 21:05, Ken Ning <kenscholar2008@gmail.com> wrote: >> Hi Nick, >> >> Thanks a lot for this. >> >> As I have many groups， I tried this following your suggestion >> >> bysort year (id) : gen diff = value[_n] - value[_n-1] >> >> >> but it says "factor variables and time-series operators not allowed" >> >> What did i do wrong? >> >> Many thanks >> Lutao >> >> >> >> On 19 August 2013 20:43, Ken Ning <kenscholar2008@gmail.com> wrote: >>> Hi statausers >>> >>> how do you subtract the value of one group from the value of another group? >>> >>> e.g. if i want to substract the value of group 2 (value= 11 in 2001 >>> and 12 in 2002) from group1 (value= 7 in 2001 and 8 in 2002) year by >>> year? so this needs to be 11-7 and 12-8 and listed next to the value >>> of group 2 >>> >>> >>> >>> id year value (minus value) >>> 1 2001 7 . >>> 1 2001 7 . >>> 1 2001 7 . >>> 1 2002 8 . >>> 1 2002 8 . >>> 1 2002 8 . >>> >>> 2 2001 11 x (need to get) >>> 2 2001 11 x >>> 2 2001 11 x >>> 2 2002 12 x >>> 2 2002 12 x >>> 2 2002 12 x >>> >>> Many thanks >>> Ken >>> * >>> * 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/ * * 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/