|
|  |
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]
st: Re: attributable fraction
I have calculated several attributable fractions.
When the AF comes up as negative however, Stata does
not display a standard error and confidence interval.
Why?
. logistic incident_lowback age gender hours_week
second_job strain xfer posi manual
incident_l~k Odds Ratio Std. Err. z P>z [95% Conf.
Interval]
age .9849692 .0149313 -1.00 0.318 .9561349 1.014673
gender .9118571 .3196976 -0.26 0.792 .4586644 1.812836
hours_week 1.000273 .0169735 0.02 0.987 .9675525
1.034099
second_job 1.0135 .3644665 0.04 0.970 .5008663
2.050812
strain 2.311378 .7130899 2.72 0.007 1.262595 4.231337
xfer 1.658223 .4354864 1.93 0.054 .9910564 2.774517
posi .7943614 .2137511 -0.86 0.392 .4687834 1.346059
manual 1.025606 .0583063 0.44 0.657 .9174643 1.146494
. aflogit posi, ref(posi=1)
Term Ref. A.F. s.e. [95% Conf. Int.]*
posi 1 -0.2742 . . .
TOTAL -0.2742 . . .
Any thoughts? Why can't you have a negative AF?
Marc
*
* 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/
