DanBos Tracker
https://communities.sas.com/kntur85557/tracker
DanBos TrackerSun, 08 Sep 2024 17:26:11 GMT2024-09-08T17:26:11ZEstimated probabilities of event in logistic regression are equivalent to crude event rates
https://communities.sas.com/t5/Statistical-Procedures/Estimated-probabilities-of-event-in-logistic-regression-are/m-p/278756#M14714
<P>Hi all,</P><P>I have a large dataset (19k) and I am using logistic regression to estimate probabilities of experiencing an event at the patient level. I am interested in looking at the effect of a facility characteristic on the odds of said event. This facility characteristic is naturally continuous and I have constructed quartiles. I calculated the crude rate of event within each quartile. When I call for the predicted probabilities from a logistic regression model with patient and disease characteristics, the mean predicted probabilities of event across the facility-characteristic quartiles are very similar to each other as well as the overall crude rate (within a thousandth). I am struggling to understand the following: when I add facility-characteristic quartile to the above model and call for the predicted probabilities, the means of the probabilities of event across the factility-characteristic quartiles are equivalent to the crude rates. I understand that the mean of the predicted probabilities will be equivalent to the crude rates across facility-characteristic quartiles when it is the only predictor in the model, but it is not here. Can anyone help me understand why this is? Happy to provide coefficients and output. </P><P> </P><P>With much appreciation!</P>Mon, 20 Jun 2016 17:36:11 GMThttps://communities.sas.com/t5/Statistical-Procedures/Estimated-probabilities-of-event-in-logistic-regression-are/m-p/278756#M14714DanBos2016-06-20T17:36:11Z