Methods for obtaining menstrual-cycle data in menstrual-synchrony studies: commentary on Schank (2001)

J. C. Schank (2001) claimed to identify 2 categories of error-measurement error and recall biases-in the methodology used in studies of menstrual synchrony. This commentary focuses on the 2nd of these, recall biases, and other errors that he argued may result from "allowing participants to fill out menstrual-cycle-onset calendars" (p. 3). J. C. Schank's detailed discussion of various types of recall biases is inappropriate and misleading given that the majority of menstrual-synchrony studies have used prospective menstrual calendars. The use of menstrual calendars is a well-accepted method in a number of research areas and demands little of participants. J. C. Schank questioned the validity of menstrual calendar data on the basis of assumptions about recall bias for which he had no evidence.