Re: st: Predicted probabilities in graph

[Steven Samuels <sjhsamuels@earthlink.net>]

Richard,

Try this.

-Steve

/***************************************************************/
sysuse auto,clear
svyset _n
tab foreign

local rhvar "mpg weight"

svy: logit foreign `rhvar'
predict phat

adjust `rhvar', gen(xb se) se

/*Compare Prediction at Mean to Actual Proportion */
gen p2=exp(xb)/(1+exp(xb))
sum phat p2

foreach v of varlist `rhvar' {
egen m`v' = mean(`v')
gen xb_`v' = xb + _b[`v']*(`v' - m`v')
gen pred_`v'=exp(xb_`v')/(1+exp(xb_`v'))
label var pred_`v' "Est Prob"
}


foreach v of varlist `rhvar' {
twoway scatter pred_`v' `v', title("Plot of Prediction against `v'"  
"Other Predictors at their Mean") saving(graph_v', replace)
}
/*********************************************************************/

On Aug 28, 2008, at 8:07 AM, Richard Ohrvall wrote:


> Hi!
>
> I am trying to illustrate predicted probabilities for a successful
> outcome in a logistic regression, e.g. when one independent variable
> goes from min to max when all other variables are kept at their mean.
>
> This can be done by using the user-written program -prgen- by J. Scott
> Long and J. Freese and the way that they explain in their book
> Regression Models for Categorical Depedent Variables Using Stata
> (2006), Stata Press. However, according to the book, the program can
> not be used when data comes from a complex sample, i.e.  when prefix
> svy is used.
>
> Since I mainly use survey data with complex sample design, this is a
> problem for me if I want to present the confidence intervals in the
> graph. Therefore, I wonder if there is some other program or some
> other way to make predicted probabilities for such graphs when taking
> the sampling design into account when estimating the confidence
> interval?
>
> Any help would be appreciated.
>
> Richard
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