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# Re: st: testing differences between coefficients

 From Maarten Buis To statalist@hsphsun2.harvard.edu Subject Re: st: testing differences between coefficients Date Thu, 20 Dec 2012 11:57:51 +0100

```An effect is a comparison, what you seem to want is a comparison of
comparisons. But before you can do that you need to define your first
comparison (effect). Now we are back at my previous advise: define

-- Maarten

On Thu, Dec 20, 2012 at 11:46 AM, Ebru Ozturk <ebru_0512@hotmail.com> wrote:
> You say it requires two or more groups. But what happens if I want to run two models with different dependent variables and with equal sample size and same independent variables, and compare the mean effect of X variable between those two models.
>
> Kind regards
> Ebru
>
> ----------------------------------------
>> Date: Thu, 20 Dec 2012 11:26:40 +0100
>> Subject: Re: st: testing differences between coefficients
>> From: maartenlbuis@gmail.com
>> To: statalist@hsphsun2.harvard.edu
>>
>> On Thu, Dec 20, 2012 at 10:49 AM, Ebru Ozturk wrote:
>> > As far as I understand your e-mail, I want to do the comparison by looking at the difference. I do not do any group separation as I just focus on two different dependent variables. In terms of what is being compared (means, probabilities, odds etc.) I really do not know. How can I decide about that? or Does it depend on the model I use?
>>
>> A difference requires two or more groups. I cannot be diffrent from
>> myself. It does not have to be two groups; you can think of a linear
>> effect as a comparison of an infinite number of groups.
>>
>> A difference also requires an idea of what is being compared, and the
>> decision depends on what interests you. You are probably very happy
>> about the fact that I am not in a position to decide for you what you
>> find interesting.
>>
>> The model is only there to estimate what you want to estimate, so the
>> model is irrelevant at this stage. Your first step is to decide what
>> you want to estimate, and than look for or derive a model that does
>> what you want.
>>
>> I'll repeat this one final time: You need to do this on your own. It
>> is not because I am mean(*) and don't want to help you, but this is a
>> question that can only be answered by you.
>>
>> -- Maarten
>>
>> (*) I might or might not be, I'll leave that to others to decide.
>>
>> ---------------------------------
>> Maarten L. Buis
>> WZB
>> Reichpietschufer 50
>> 10785 Berlin
>> Germany
>>
>> http://www.maartenbuis.nl
>> ---------------------------------
>>
>> *
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--
---------------------------------
Maarten L. Buis
WZB
Reichpietschufer 50
10785 Berlin
Germany

http://www.maartenbuis.nl
---------------------------------

*
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```