RT Article T1 Are Relational Inferences from Crowdsourced and Opt-in Samples Generalizable? Comparing Criminal Justice Attitudes in the GSS and Five Online Samples JF Journal of quantitative criminology VO 36 IS 4 SP 907 OP 932 A1 Thompson, Andrew J. A2 Pickett, Justin T. LA English YR 2020 UL https://krimdok.uni-tuebingen.de/Record/1745751750 AB Similar to researchers in other disciplines, criminologists increasingly are using online crowdsourcing and opt-in panels for sampling, because of their low cost and convenience. However, online non-probability samples’ “fitness for use” will depend on the inference type and outcome variables of interest. Many studies use these samples to analyze relationships between variables. We explain how selection bias—when selection is a collider variable—and effect heterogeneity may undermine, respectively, the internal and external validity of relational inferences from crowdsourced and opt-in samples. We then examine whether such samples yield generalizable inferences about the correlates of criminal justice attitudes specifically. K1 Opt-in panel K1 Amazon Mechanical Turk K1 Collider variable K1 Selection Bias K1 Web survey K1 Selection bias DO 10.1007/s10940-019-09436-7