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| From | Maarten Buis <maartenlbuis@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | merging and sample size [was: Re: st: Re: ESTIMATING THE LA/AIDS MODEL] |
| Date | Wed, 13 Jun 2012 14:40:00 +0200 |
On Wed, Jun 13, 2012 at 2:27 PM, daniel milandu wrote: > after merging data sets is my sample size supposed to increase That can happen when the "using dataset" (the dataset you specified after -using-) contains observations form which no match was found in the master dataset (the dataset that was open when you called -merge-). After merging you can see where each observation comes from (i.e. both datasets, only the master, or only the using dataset) by looking at the variable _merge. You can than decide whether this represents a problem or that you can safely drop (some) unmatched observations. Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * 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/