Possessives and Attributives

Q. An editor for a journal using the CMOS 15th edition has changed all of my plural possessives (patients’ suffering, positivists’ project) to, e.g., patients’s suffering, positivists’s project. This is incorrect. The former, not the latter, is correct. Yes?

A. The former is correct—and let’s hope this was just one of those momentary brain misfires that even the best editors occasionally suffer. Please see CMOS 7.15 (7.17 in the 15th edition).