Critique of a study on ganja in Jamaica

In the study of "Ganja in Jamaica" by Rubin and Comitas, no significant differences between heavy ganja smokers and controls could be demonstrated in physical and psychological symptoms or social adjustment. This lack of difference may be attributed to methodological limitations in the sampling technique and examinations performed. The number of subjects studied was small (30 in both control and test group). The selection of controls was inadequate: only 12 controls had never smoked ganja, and 8 were current occasional users. Methodological limitations flawed the physical examinations of the lung and cardiovascular system, cytogenetic studies, psychological assessment and psychiatric evaluation. Acceptance by the authors of a positive motivational influence of cannabis smoking and other socially beneficial properties of such smoking was based more on philosophical premises than on objective observations performed by others in Jamaica and other countries.