\r\nThe same screening test is applied to two comuunities X and Y; Y shows more false +ve cases as compared to X. The possibility is:

The number of false positives will be more, when the prevalence is less because, the predictive value of a test and hence its ability to identify the true positive is decreased. Therefore Y shows more false positives because the prevalence of disease in question in Y community is low. Ref: Park's Textbook of Preventive and Social Medicine By K. Park, 19th Edition, Page 119