Last year I wrote a post about how in linear regression the mean (and sum) of the residuals always equals zero, and so checking that the overall mean of the residuals is zero tells you nothing about the goodness of fit of the model. Someone asked me recently whether the same is true of logistic regression. The answer is yes for a particular residual definition, as I’ll show in this post.
Logistic regression / Generalized linear models
Why shouldn’t I use linear regression if my outcome is binary?
This week a student asked me (quite reasonably) whether using linear regression to model binary outcomes was really such a bad idea, and if it was, why. In this post I’ll look at some of the issues involved and try to answer the question.
Interpreting odds and odds ratios
Odds and odds ratios are an important measure of the absolute/relative chance of an event of interest happening, but their interpretation is sometimes a little tricky to master. In this short post, I’ll describe these concepts in a (hopefully) clear way.