Characteristics of research volunteers for inpatient cocaine studies: Focus on selection bias

In order to investigate the selection bias of subjects for inpatient human cocaine studies, characteristics of 859 potential subjects were examined. E xcluded subjects compared with accepted group were more likely to be single and male, currently use drugs other than cocaine, have a history of intrav enous cocaine use, and have medical or mental health problems or physical c omplaints. Subjects who were accepted but did not participate, compared wit h participants, were likely to spend more money on cocaine. These results s uggest that potential subjects who were accepted to our research studies ma y not accurately represent all potential subjects for several important sub ject characteristics. (C) 2000 Elsevier Science Ltd.