Re: st: How test linear combination of estimates from two sets of results from margins?

[Maarten Buis <maartenlbuis@gmail.com>]

On Mon, Mar 4, 2013 at 12:57 AM, Hanig, Ross wrote:
> I am running an ordered logit and using the command margins to get point estimates at different values of my dependent and independent variables (both on a 5 point likert scale). I need to test a linear combination of a point estimate from one margins command minus a point estimate using another margins command. Any ideas on how to do this?

Did your ordered logit model include an interaction term between
scenario and windsupport_b4comp? If that is not the case, than your
test has no substantive meaning; any differences your will find is
only the result of the specifc non-linearity in the ologit model,
which you certainly do not want to take so serious as to interpret the
test you propose.

I also think that you do not want to use the -if- condition in
-margins- the way you have done. It looks to me that you will want to
use either the -at()- or -over()- option for that.

Below is an example of how I would solve your problem. Male takes the
role of scenario in your problem and ed the role of
windsupport_b4comp.

*------------------ begin example ------------------
use "http://www.indiana.edu/~jslsoc/stata/spex_data/ordwarm2.dta";, clear
ologit warm white i.male##c.ed prst yr89 age

margins, at(male=(0 1) ed=(8 12 14 16)) atmeans post
test (1._at=5._at) ///
     (2._at=6._at) ///
     (3._at=7._at) ///
     (4._at=8._at)
*------------------- end example -------------------
(For more on examples I sent to the Statalist see:
http://www.maartenbuis.nl/example_faq )

Hope this helps,
Maarten

Ps. it is Likert scale not likert scale, as the scale was named after
a person, Rensis Likert.

---------------------------------
Maarten L. Buis
WZB
Reichpietschufer 50
10785 Berlin
Germany

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

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