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From | Nick Cox <njcoxstata@gmail.com> |
To | "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
Subject | Re: st: Counting number of observations in the following 4 years |
Date | Thu, 20 Feb 2014 00:46:59 +0000 |
I don't understand what this means. I guess that "keep" means -keep-, or inversely not -drop-. Suppose X is present in years 1,2,3,4,5,6,7,8 but not in 9,10. So I keep observations in years 1 to 4 because everything in year 5 to 8 is OK. But now I don't keep 5 or 6 or 7 or 8 because 9 and 10 are missing. But that means the decisions for earlier observations should now be revisited, and I end up dropping everything. In general, if you have missing values in time series you can just -drop- the missing values and/or let Stata do its best. The two are usually equivalent. Anything else is likely to mean just losing information capriciously and unnecessarily. . Nick njcoxstata@gmail.com On 20 February 2014 00:24, micdepo mic <micdepo@gmail.com> wrote: > Hi, > > I have data on variable X for a period of time. I am trying to count > for every given year t the number of future observations on X in the > following 4 years. I will keep this year's observation X_t iff I know > for sure X_t+k is not missing for k=1,2,3,4 (i.e. I have data on X for > every year in the next four years). This will go on for every year t > from t=1 to T. I would be most grateful if you could please tell me > the easiest way to do this kind of operation. Thanks very much in > advance. > > Best regards, > Mic > * > * 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/