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From | Verena Dill <dill@uni-trier.de> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: Testing interaction terms |
Date | Wed, 19 Jun 2013 14:06:49 +0200 |
var1: variable 1 (dummy) var2: variable 2 (dummy) interaction: interaction of variable 1 and variable 2 tab var1 var2 var1 | var2 | 0 1 | Total -----------+----------------------+---------- 0 | 0 122 | 122 1 | 322 256 | 578 -----------+----------------------+---------- Total | 322 378 | 700Since no observations exist for var1==0 & var2==0 I can only include the interaction and one of the variables (just to mention that: From a theoretical sense it makes sense to do so): "probit var1 interaction" Now I want to test if I can reject the hypothesis that _b[var1]=_b[interaction]. If I use the standard command "test" it does not account for the fact that these variables are related.
Because of the nature of my variables I wanted to use the "contrast" command but this only works if I'd use something like this before: "probit var1##var2" which is not solvable because of the above mentioned fact that var1==0 & var2==0 does not exist in the data.
Can anybody suggest another command that takes into account that the two variables are interacted or has ideas on how to adjust the "contrast"-command?
Any help is greatly appreciated! Verena * * 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/