Using the coefficients obtained through my regression (logit), I am trying to write the equation in Excel so that I can demonstrate the effect of each variable on the probable outcome. However, the probabilities that result do not match the probabilities of my SAS-scored individuals.
In Excel, I'm doing it in two steps. The first step is:
Then in the neighboring cell, I take that result and use it in this equation:
= 1/(1+(EXP((-1)*(result from above))))
The resulting probability is not equal to what SAS generates when the dataset is scored.
I'm not sure if this is related to my problem or not, but my dichotomous coefficients (levels are 0 or 1) that have negative estimates (for the 0 level) have a positive effect on probability. When I manipulate these in my equation, I'm observing the opposite.
SAS may be estimating the probabilty for the other outcome, i.e., SAS is estimating the probabilty of outcome 1, while your excel formula may be estimating the prob for outcome 0. This would explain your opposite coefficients, as well.