SUMMARY
Some guidelines for interpreting prevalence estimates for the purpose of establishing the number of pathological gamblers in the community are presented. The analysis is based on the concept of the likelihood ratio, a recommended procedure for validating criteria for defining cases based on test scores. It is shown that the likelihood ratio can be employed with available estimates of prevalence to translate cut-off scores into positive predictive value. Those cut-off scores associated with high positive predictive values provide an empirical measure of confidence that those gamblers who meet or exceed the cut-off criterion are pathological gamblers. A potential limitation of the analysis is the possible specificity of results to the validation studies employed to compute likelihood ratios and to the specific estimates of prevalence used to determine positive predictive value. A recommendation is presented for obtaining study- or community-specific validation evidence.