# Use propensity score or logit propensity score as distance metric for control group selection?

My question is a bit of a general one (and my first on here). I'm researching different matching methods for selecting a control group in an observational study, and when checking SAS's options for proc PSMATCH, there's an option to use either the raw propensity score (PS) or the logit propensity score (LPS) as the distance metric between control and program group members.

My question is - in what situations would it be appropriate to use the PS as a distance metric as opposed to the LPS? Or, maybe more broadly, how might I determine when it's appropriate with a given set of data?

• Although this question mentions SAS, I think it's pretty clearly on topic. It's about statistics, not programming. – Peter Flom - Reinstate Monica May 18 '18 at 10:46