# st: relative risk from relrisk.ado vs. rrr in multinomial regression

 From "Ssu Weng" To Subject st: relative risk from relrisk.ado vs. rrr in multinomial regression Date Sat, 4 Oct 2003 19:25:41 -0600

```I'd like to estimate relative risks in addition to odds ratios.
Why do I get the same estimates from -or- option after -logit- as from -rrr-
after -mlogit-, but different estimates from -relrisk-?
When using -mlogit- or -svymlogit- and option -rrr-, are the estimates
actually odds ratios?  If so,
how can I get relative risks from multinomial regression?

In the output below, I'm just using a binary outcome variable as an example.
Actually, I want to use -svymlogit- for a 4-level outcome variable.

Ssu Weng
ssuweng@comcast.net

. logit APNCB PP_5X1 PP_5X2 PP_5X3 PP_5X5, or

Logit estimates                                   Number of obs   =
5632
LR chi2(4)      =
66.44
Prob > chi2     =
0.0000
Log likelihood = -3661.7963                       Pseudo R2       =
0.0090

----------------------------------------------------------------------------
--
APNCB | Odds Ratio   Std. Err.      z    P>|z|     [95% Conf.
Interval]
-------------+--------------------------------------------------------------
--
PP_5X1 |   1.865625   .1609324     7.23   0.000     1.575426
2.209279
PP_5X2 |   .9794411   .1370441    -0.15   0.882     .7445222
1.288484
PP_5X3 |   1.395263   .0915377     5.08   0.000     1.226908
1.586719
PP_5X5 |    1.54276   .1649583     4.05   0.000     1.251078
1.902446
----------------------------------------------------------------------------
--

. relrisk
Po             Rel Risk       Lower Limit    Upper Limit
RR PP_5X1:         0.350          1.432          1.311          1.552
RR PP_5X2:         0.368          0.987          0.822          1.165
RR PP_5X3:         0.353          1.224          1.136          1.314
RR PP_5X5:         0.361          1.290          1.147          1.435

. mlogit APNCB PP_5X1 PP_5X2 PP_5X3 PP_5X5, rrr

Multinomial regression                            Number of obs   =
5632
LR chi2(4)      =
66.44
Prob > chi2     =
0.0000
Log likelihood = -3661.7963                       Pseudo R2       =
0.0090

----------------------------------------------------------------------------
--
APNCB |        RRR   Std. Err.      z    P>|z|     [95% Conf.
Interval]
-------------+--------------------------------------------------------------
--
1            |
PP_5X1 |   1.865625   .1609324     7.23   0.000     1.575426
2.209279
PP_5X2 |   .9794411   .1370441    -0.15   0.882     .7445222
1.288484
PP_5X3 |   1.395263   .0915377     5.08   0.000     1.226908
1.586719
PP_5X5 |    1.54276   .1649583     4.05   0.000     1.251078
1.902446
----------------------------------------------------------------------------
--
(Outcome APNCB==0 is the comparison group)

** APNCB is a common outcome

. tab APNCB

APNCB |      Freq.     Percent        Cum.
------------+-----------------------------------
0 |       3592       62.90       62.90
1 |       2119       37.10      100.00
------------+-----------------------------------
Total |       5711      100.00

*
*   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/
```