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From | Maarten Buis <maartenlbuis@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Obtaining rrr's of margins after mlogit |
Date | Thu, 22 Mar 2012 13:56:35 +0100 |
On Thu, Mar 22, 2012 at 12:03 PM, John Francis wrote: > Now, what do I do in order to check how much the effect has changed > between cohorts, and whether or not said change is significant? How > does the constant play into this? I think these things would be fairly > obvious to see if I could use -margins, over()-, but as it is, the > -mlogit- output is quite confusing to me... I think what you are looking for what is discussed in M.L. Buis (forthcoming) "Stata tip 106: With or without reference", The Stata Journal, 12(1). <http://www.maartenbuis.nl/publications/ref_cat.html> With these tricks you can easily get separate relative risk ratios for each category, which is sometimes easier to understand. To create an example with -mlogit-: *------------------------ begin example ------------------------- sysuse nlsw88, clear gen occ_cat = cond(occupation < 3 , 1, /// cond(inlist(occupation, 5, 6, 8, 13), 2, 3)) /// if occupation < . label define occ_cat 1 "high" /// 2 "middle" /// 3 "lower" label value occ_cat occ_cat gen marst = never_married + 2*married label define marst 1 "divorced/widowed" /// 2 "never married" /// 3 "married" label value marst marst gen c_grade = grade - 12 mlogit occ_cat ibn.marst ibn.marst#c.c_grade, rrr nocons *------------------------- end example -------------------------- (For more on examples I sent to the Statalist see: http://www.maartenbuis.nl/example_faq ) So the relative risks comparing high with lower occupations (in the panel labeled "high") for divorced/widowed is .54 person with a higher job for every person with a lower job. Similarly, for never married it is .38 person with a higher job for every person with a lower job and for married it is .43 persons with a higher job for every person with a lower job. All these relative risks (I like to call them odds [*]) refer to persons with high school (12 years of education). A year increase in education is associated with an increase in the relative risks by a factor 1.23, 1.44, and 1.29 for divorced/widowed, never married, and married persons respectively. Hope this helps, Maarten [*] <http://www.stata.com/statalist/archive/2007-02/msg00085.html> -------------------------- 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/