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| From | Maarten Buis <maartenlbuis@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: How to drop individuals from sample? |
| Date | Wed, 25 Jul 2012 09:25:22 +0200 |
On Wed, Jul 25, 2012 at 8:54 AM, Dheepan Ratha Krishnan wrote: > I am looking for a stata > command that will enable me to exclude individuals who have > experienced a particular life event more than once in my dataset. That depends on how your data is structured. I will assume that the data has the following structure: Each event has its own record, so the same individual can have multiple records. The type of event is stored in a separate variable, for example: person event_date event_type other_vars 1 02Jan2012 married ... 1 03Jan2012 divorced ... 1 04Jan2012 married 2 01Feb1950 married ... 2 01Jun2012 widowed .... In this case you would want to ignore person 1 as he married twice (in three days...). Typically you do not have the variable event_type as a string but as a numeric variable with labels attached. Say 1 is married 2 is divorced and 3 is widowed, and you are interested in the event married. Than you type: gen byte married = event == 1 bys person : egen tot_married = total(married) drop married The variable tot_married counts the number of times a person got married, so you want to ignore all persons with tot_married > 2. So you add to any subsequent command the condition -if tot_married < 2-. This way you ignore the entire person 1, but say you want to use the first marriage of person 1 just not any subsequent marriages. Than you type: gen byte married = event == 1 bys person (event_date) : gen tot_married = sum(married) drop married To read more about this see: http://www.stata.com/support/faqs/data-management/true-and-false/ help egen help sum() help if 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/