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As in a subject.
data have; set sashelp.cars; isUSA = Origin="USA"; run; proc logistic data=have; model isUSA=EngineSize Cylinders Horsepower; output out=pred p=p; run; data want; keep p p_manual; set pred; p_manual = 1/(1+EXP(-1 * 0.3199 -3.091*EngineSize +0.5735*Cylinders +0.0334*Horsepower)); run;
Why is p different than p_manual variable in the want dataset?
Thanks.
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- proc logistic
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How different?
Here's an example showing results that match exactly.
https://communities.sas.com/t5/Statistical-Procedures/How-to-determine-logistic-regression-formula-f...
You were missing a set of brackets in your formula:
p_manual = 1/(1+EXP(-1 * (0.3199 -3.091*EngineSize +0.5735*Cylinders +0.0334*Horsepower)));
@Jedrek369 wrote:
As in a subject.
data have; set sashelp.cars; isUSA = Origin="USA"; run; proc logistic data=have; model isUSA=EngineSize Cylinders Horsepower; output out=pred p=p; run; data want; keep p p_manual; set pred; p_manual = 1/(1+EXP(-1 * 0.3199 -3.091*EngineSize +0.5735*Cylinders +0.0334*Horsepower)); run;Why is p different than p_manual variable in the want dataset?
Thanks.
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How different?
Here's an example showing results that match exactly.
https://communities.sas.com/t5/Statistical-Procedures/How-to-determine-logistic-regression-formula-f...
You were missing a set of brackets in your formula:
p_manual = 1/(1+EXP(-1 * (0.3199 -3.091*EngineSize +0.5735*Cylinders +0.0334*Horsepower)));
@Jedrek369 wrote:
As in a subject.
data have; set sashelp.cars; isUSA = Origin="USA"; run; proc logistic data=have; model isUSA=EngineSize Cylinders Horsepower; output out=pred p=p; run; data want; keep p p_manual; set pred; p_manual = 1/(1+EXP(-1 * 0.3199 -3.091*EngineSize +0.5735*Cylinders +0.0334*Horsepower)); run;Why is p different than p_manual variable in the want dataset?
Thanks.
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Shoot. That's embarrassing. Thanks anyway.
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Tip: The formula
p_manual = 1/(1+EXP(-1 * (...)));
can be simplified to
p_manual = logistic(...);
(see LOGISTIC function).