Abstract
Hicks-Caskey and Potter (1991) claim to have found a “full moon effect” on women in a developmental center. Further, they suggest the discrepancies in findings on lunar effects can be accounted for by (i) a lack of equivalent operational definitions and (ii) a person selection factor. It is argued that the Hicks-Caskey and Potter findings are undermined by weekday, holiday, season, weather, particular staff-subject interactions, and expectancy effects. In addition, the proposed explanations for differing outcomes in lunar studies do not explain both the negative findings and conflicting positive findings.
