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From | Abhimanyu Arora <abhimanyu.arora1987@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Merging longitudinal data set |
Date | Sat, 17 Jul 2010 00:16:29 +0200 |
Or -merging- and -reshape- ? On Sat, Jul 17, 2010 at 12:11 AM, Abdel Rahmen El Lahga <rahmen.lahga@gmail.com> wrote: > I think that your strategy is wrong. When you have a panel data (each > wave in a separate file) I suggest th command "append" instead of > "merge". > "append" will concatunate vertically your waves and the final data set > could be analyzed as panel. I presule that you have a variable year > identifying tha wave date. If not you should create such variable > before appending file. > Before further analysis see the commands "xtset" "xtdes"...:) > AbdelRahmen > > 2010/7/16 Andreas Jensen <bentrevisor@gmail.com>: >> Hi Statalist. >> >> I'm a new Stata user (previously only used R) and I'm working on a >> project involving a longitudinal data set. There are two waves each >> contained in its own data file and there is a common ID variable which >> is consistent among the waves. I'm trying to wrap my head around the >> merge command and I'm sure this is a fairly basic question. I, >> however, would appreciate some confirmation on that what I'm doing is >> hopefully correct. >> >> What I'm troubled about is that there are people from wave 1 that has >> dropped out when wave 2 was conducted (their ID does not exist in the >> wave 2 data file), and there has been added additional people in wave >> 2 that aren't present in wave 1 (their ID does not exist in the wave 1 >> data file). >> >> I have sorted each data file according to the ID variable and then >> executed a merge 1:1 on the ID with wave 1 as master. I get the >> following output. >> >> Result # of obs. >> ----------------------------------------- >> not matched 28,046 >> from master 12,373 (_merge==1) >> from using 15,673 (_merge==2) >> >> matched 18,742 (_merge==3) >> ----------------------------------------- >> >> So assuming that my command is correct, is it then true that there are >> 18742 individuals in both waves, 12373 individuals which has dropped >> out after wave 1 and 15673 individuals that have been added in wave 2? >> >> Thanks in advance, >> Andreas Jensen >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/statalist/faq >> * http://www.ats.ucla.edu/stat/stata/ >> > > > > -- > AbdelRahmen El Lahga > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/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/statalist/faq * http://www.ats.ucla.edu/stat/stata/