 Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.

RE: st: AW: confidence interval of a ratio of coefficients

 From Rodolphe Desbordes To "'statalist@hsphsun2.harvard.edu'" Subject RE: st: AW: confidence interval of a ratio of coefficients Date Fri, 9 Apr 2010 16:26:04 +0100

Martin and Nick,

Very true:

***
sysuse auto, clear
set seed 2940688
logit foreign price weight rep78

preserve

drawnorm b1-b4, n(20000) means(e(b)) cov(e(V)) clear

gen ratio=-(b2)/(b1)

qui sum ratio,meanonly

dis "ratio: " r(mean)

qui _pctile ratio, p(2.5,97.5)

dis "ll: " r(r1)
dis "ul: " r(r2)

restore

***

Rodolphe

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
Sent: vendredi 9 avril 2010 16:17
To: statalist@hsphsun2.harvard.edu
Subject: RE: st: AW: confidence interval of a ratio of coefficients

Even for another purpose, using -egen- to create a variable containing a
single mean is hideously inefficient. Use -su, meanonly- and pick up
r(mean) afterwards.

Nick
n.j.cox@durham.ac.uk

Rodolphe Desbordes

Some leftover from another code. It is useless in that code.

Martin Weiss

What is your -egen- line good for?

Rodolphe Desbordes

Would this approach make sense?

sysuse auto, clear
set seed 2940688
logit foreign price weight rep78

preserve

drawnorm b1-b4, n(20000) means(e(b)) cov(e(V)) clear

gen ratio=-(b2)/(b1)

egen mean=mean(ratio)

_pctile ratio, p(2.5,97.5)
gen ll=r(r1)
gen ul= r(r2)

sum ratio ll ul

restore

*
*   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/