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From | Joerg Luedicke <joerg.luedicke@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Fwd: How to interpret regression? |
Date | Tue, 25 Sep 2012 08:57:08 -0500 |
It seems that you are more concerned about p-values than you are concerned about what you can actually learn about your data by fitting this model. It looks to me as if you are interested in measuring a non-linear effect of wealth on your outcome that differs across the groups defined by your dummy variables. If this is correct I would start with inspecting the bivariate relations between your outcome and wealth and check if this relation differs across your groups (for example using a smoother like -lowess- or -lpoly-). Depending on how these relations look like it could make sense to summarize them using a model that includes (perhaps 2nd or 3rd order) polynomial terms for wealth, which would be one convenient possibility. Of course, it can always be checked how good of a summary that would be, given your data. In any case, I find it hard to see why you would include wealth as a continuous variable and a categorical version of wealth in the same model. In any case, you should perhaps provide more information about your research question, variables etc. Just saying that some inputs xyz are significant in one model but not in another is probably not very helpful in order to get reasonable advice. Joerg On Tue, Sep 25, 2012 at 7:05 AM, Kresten Buch <krestensb@gmail.com> wrote: > Dear Statalist, > > I have problems figuring out what I can interpret from this > regression. Could you please help me? > > I regress a taxation measure against 4 dummies and their interaction > with a measure of wealth, and interaction between the 4 dummies and > a dummy constructed from the measure of wealth, where I give the value > 1 to observations in the top 10% or bottom 10% of the wealth measure, > and 0 to the rest of the observations. > > If I include all variables in the model, I get significant effects > from both sets of interaction variables. If only one set is included, > then I nothing is significant, no matter witch one is excluded. > > I hope the explanation makes sense ? > > -- > Best regards from Kresten Buch, Denmark > * > * 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/