Gambling behavior is pervasive, apparently growing, and of methodological and substantive interest to economists. We examine the manner in which the population prevalence of disordered gambling has been estimated. General population surveys have deepened our knowledge of the population prevalence of gambling disorders, as well as the manner in which gambling disorder is associated with other mental health problems. However, we identify a fundamental bias in the manner in which these surveys have been used to draw inferences about the general population prevalence of gambling problems, due to a behavioral response to seemingly innocuous “trigger,” “gateway” or “diagnostic stem” questions in the design of surveys. Formal modeling of the latent sample selection behavior generated by these trigger questions leads to dramatically different inferences about population prevalence and comorbidities with other psychiatric disorders. The population prevalence of problem or pathological gambling in the United States is inferred to be 7.7% rather than 1.3% when this behavioral response is ignor ed. Comorbidities are inferred to be much smaller than the received wisdom, particularly when considering the marginal association with other mental
health problems rather than the total association. The issues identified here apply, in principle, to every psychiatric disorder covered by these surveys, and not just gambling disorder. We discuss ways in which these behavioral biases can be mitigated in future surveys.