Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

Correction to Ada (Was Re: st: Questions on -mlogit-)


From   "Clive Nicholas" <Clive.Nicholas@newcastle.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Correction to Ada (Was Re: st: Questions on -mlogit-)
Date   Sun, 28 Mar 2004 00:10:48 -0000 (GMT)

I should issue a hasty correction to Ada. She was, of course, talking
about _probabilities_ in calculating:

>> exp(1.96e-17)/(1+exp(1.96e-17))
>>
>> Not 1/1.96e-17 as you have used.

This I've done, and P = .368. Thanks to her for this. However, I believe
I'm correct in its interpretation (i.e., since the odds < 1, P must be <
.5, given the hypothesis I stated).

So that's that sorted. My second query was the log_10 of the Hessian
condition number. Maybe I should be clearer in what I'm looking for. In
order to calculate this figure, we take the square root of the largest and
smallest roots in the variance-covariance matrix. I know what to do once
I've obtained that ratio:

. display log10(ratio)

but how do I obtain these two roots from the matrix?

CLIVE NICHOLAS        |t: 0(44)191 222 5969
Politics              |e: clive.nicholas@ncl.ac.uk
Newcastle University  |http://www.ncl.ac.uk/geps
*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index