I don't see what you are referring to, Wendell. The p-values
(labeled "P>|Z|") appear to be changing to me. What did not
change is Po, which is defined as "the incidence of the outcome
(dependent variable = 1) in the unexposed group." This should not
change based on # of predictors in the model.
Tom
> -----Original Message-----
> From: Wendell Joice [mailto:[email protected]]
> Sent: Wednesday, July 16, 2003 4:55 PM
> To: [email protected]
> Subject: st: relative risk
>
>
> I am using Stata 7 and the -relrisk- (ado) command in conjunction
> ith -logistic-. I note that, for my data, the p value (for a given
> covariate) never changes, regardless of how many or which
> variables I add to
> the model. For example, in the data below, I am using a
> dependent variable
> (psyment) with a covariate (racewbh). The relative risk ratios for
> _Iracewbh_2 & _Iracewbh_3 change as I add other covariates
> to the model;
> but the p value for these two variables never changes (see
> small and large
> models below).
>
> Is this the way it should be or am I in error with my data?
> My usage of
> the -relrisk- command?
> Is there a simple way to check (verify) the output of the
> -relrisk- command?
>
> Thanks,
> Wendell Joice
>
>
>
> SMALL MODEL
>
> xi: logistic psyment i.racewbh if csample==1
> i.racewbh _Iracewbh_1-3 (naturally coded;
> _Iracewbh_1
> omitted)
>
> Logit estimates
> Number of obs =
> 19295
> LR
> chi2(2) =
> 68.54
> Prob
> > chi2 =
> 0.0000
> Log likelihood = -12961.957
> Pseudo R2 =
> 0.0026
>
>
> ----------------------------------------------------------------------
> --------
> psyment | Odds Ratio Std. Err. z P>|z|
> [95% Conf.
> Interval]
>
> -------------+--------------------------------------------------------
> --------
> _Iracewbh_2 | .6429203 .0385832 -7.36 0.000
> .5715766
> .723169
> _Iracewbh_3 | .7907062 .0466184 -3.98 0.000
> .7044174
> .8875651
>
> ----------------------------------------------------------------------
> --------
>
> relrisk
> Po Rel Risk
> Lower
> Limit Upper Limit
> RR _Iracewbh_2: 0.066 0.658 0.588
> 0.737
> RR _Iracewbh_3: 0.065 0.802 0.718
> 0.894
>
>
> LARGER MODEL BELOW
>
> xi: logistic psyment i.racewbh i.physpecy i.psydin2
> i.phytimec i.chrcadg
> i.di
> > agsrvc i.acutcadg i.newinsur i.likreccdg i.psydrnumx
> i.agecatc
> i.GEOGREGN i.
> > yearmhp if csample==1
>
> (output abbreviated)
>
> Logit estimates
> Number of obs =
> 18110
> LR
> chi2(30) =
> 11484.07
> Prob
> > chi2 =
> 0.0000
> Log likelihood = -6465.4055
> Pseudo R2 =
> 0.4704
>
>
> ----------------------------------------------------------------------
> --------
> psyment | Odds Ratio Std. Err. z P>|z|
> [95% Conf.
> Interval]
>
> -------------+--------------------------------------------------------
> --------
> _Iracewbh_2 | .8734043 .0805943 -1.47 0.142
> .7289031
> 1.046552
> _Iracewbh_3 | .9309302 .0823622 -0.81 0.419
> .7827242
> 1.107199
> _Iphyspecy_2 | .5840736 .0408614 -7.69 0.000
> .5092348
> .6699109
> _Iphyspecy_3 | 10.01045 .8514816 27.08 0.000
> 8.473265
> 11.82649
> ..........................................Output
> abbreviated......................
>
> _Iyearmhp_6 | .4989542 .0376058 -9.22 0.000
> .4304337
> .5783824
>
> ----------------------------------------------------------------------
> --------
>
> relrisk
> Po Rel Risk
> Lower
> Limit Upper Limit
> RR _Iracewbh_2: 0.066 0.881 0.742
> 1.043
> RR _Iracewbh_3: 0.065 0.935 0.794
> 1.100
> RR _Iphyspecy_2: 0.168 0.628 0.555
> 0.709
> RR _Iphyspecy_3: 0.016 8.764 7.579
> 10.100
> ............................................Output
> abbreviated...............................
> RR _Iyearmhp_5: 0.059 0.773 0.667
> 0.896
> RR _Iyearmhp_6: 0.061 0.515 0.446
> 0.594
>
>
>
> *
> * 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/
>
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