st: how to get a two-line-graph for predicted probabilites in logistic regression model with a metric controll variable (SE10)

["Prof. Dr. Claudia Schuchart" <schuchart@uni-wuppertal.de>]

Dear statalist user,
I did a graph with SE10 for predicted probabilites in a logistic 
regression model. I controlled for intelligence (metric), and considered 
two indendent binary vaiables as well as the interaction between them 
(N=187). I want to have a two-line-graph (holding intelligence 
constant), instead I got multiple graphs for any intelligence value:
xi: logit y i.a*i.b IQ
predict y, pr
separate y, by(b)
graph twoway line y0 y1 a , xlabel(1 2)

How can I get  a two line graph only?
Claudia
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