Re: st: How to test for difference in predicted prob after prvalue

["Sebastian E. Wenz" <sewenz@rumms.uni-mannheim.de>]

Hi Kristin,

as Richard pointed out: sounds like you are interested in the discrete 
change effect(s) in the probabilities for "sex" (or whatever the name of 
your variable is, e.g. "male" to stick with Richard's example).

You might want to look (again) at page 249 in Long/Freese (2006 [2nd 
edition], section 6.6.3). They describe exactly what Richard showed in 
his example just for race instead of sex (using options -save- and 
-diff- to calculate the discrete change effect).

Note the option -rest()- which allows you to specify different values 
for your independent variables. Note further that you will end up with 
different results (different magnitude) for the discrete change when 
calculating it at different values of your covariates.

Say hi to good old Europe for me,
Sebastian (@IU Bloomington)

Richard Williams schrieb:

> At 09:55 PM 12/6/2007, Kristin J. Kleinjans wrote:
> > Dear Statalist,
> > I run 'mlogit' and use 'prvalue' to get predicted probabilities of
> > outcomes for individuals with different characteristics (as described in
> > Long and Freeses book on regressions for categorical variables). 
> > 'prvalue'
> > also returns the confidence intervals of the predicted probabilities.
> > I would like to test whether the predicted probabilities of a specific
> > outcome are different for, let's say, women with the characteristics of
> > men and average women. I hope somebody can help me on how to do this?
> >
> > Thanks a lot and best regards,
> > Kristin
> See the help for -prvalue-. The -diff- option might give you what you 
> want.  Look to see whether 0 falls within the confidence interval for 
> the change; if not, the differences are statistically significant.  
> Example:
>
> . use "http://www.indiana.edu/~jslsoc/stata/spex_data/ordwarm2.dta";
> (77 & 89 General Social Survey)
>
> . quietly mlogit  warm yr89 male white age ed prst
>
> . quietly prvalue, x(male=0) delta save
>
> . prvalue, x(male=1) delta diff
>
> mlogit: Change in Predictions for warm
>
> Confidence intervals by delta method
>
>                      Current     Saved    Change   95% CI for Change
>   Pr(y=1SD|x):        0.1311    0.0962    0.0350  [ 0.0094,   0.0606]
>   Pr(y=2D|x):         0.3952    0.2621    0.1331  [ 0.0935,   0.1726]
>   Pr(y=4SA|x):        0.0994    0.2484   -0.1491  [-0.1795,  -0.1186]
>   Pr(y=3A|x):         0.3743    0.3933   -0.0190  [-0.0601,   0.0221]
>
>                yr89       male      white        age         ed       
> prst
> Current=  .39860445          1   .8765809  44.935456  12.218055  
> 39.585259
>   Saved=  .39860445          0   .8765809  44.935456  12.218055  
> 39.585259
>    Diff=          0          1          0          0          
> 0          0
>
>
>
> -------------------------------------------
> Richard Williams, Notre Dame Dept of Sociology
> OFFICE: (574)631-6668, (574)631-6463
> HOME:   (574)289-5227
> EMAIL:  Richard.A.Williams.5@ND.Edu
> WWW:    http://www.nd.edu/~rwilliam
>
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