Teaching logistic regression and the recent discussion with Diego
Bassani made me remember a long standing wish for the output after
-logit- with the or option (which I might forget again at the "wishes
and grumbles" session at the German Stata Users' Group meeting on April
2nd): I would like to see the exp(_cons). This parameter represents the
odds of success versus failure for someone whose xs are all zero. This
helps me to assess the size of an effect. For instance, the odds ratio
may tell me that the odds of success is twice as large for women then
for men, but it makes a difference if the odds of success for men is .5
or .05.
Although I really like to see this, I realize that there are (at least)
two difficulties here:
1) Labeling. Just adding a row in the output for the constant would
suggest that it is an odds ratio, which it isn't. Maybe adding a
footnote that states that it is an odds and not an odds ratio is
enough, but that isn't the most elegant solution. Maybe as an extra
safety feature keep the current situation as the default and add an
option to see the exponentiated constant.
2) Consistency with other commands. -logit- isn't the only command that
allows for exponentiated coefficients. One of the nice things about
Stata is it's consistent output across commands, so changing the or
option for logistic would probably involve looking at all these
commands and see if a similar change to that command would make sense.
Maarten
Ps. I know you can get this with -nlcom exp(_b[_cons])-.
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
___________________________________________________________
New Yahoo! Mail is the ultimate force in competitive emailing. Find out more at the Yahoo! Mail Championships. Plus: play games and win prizes.
http://uk.rd.yahoo.com/evt=44106/*http://mail.yahoo.net/uk
*
* 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/
