Abstract
Although crowdsourcing platforms are widely used in substance-use research, it is unclear what percentage of participants use substances at the time of participation and how this might affect data quality, behavioral outcomes, or decision making. We conducted a secondary analysis of data collected on MTurk for a two-session, within-subject experiment recruiting individuals who regularly use alcohol, cannabis, cigarettes, or opioids. We analyzed 527 observations collected across two sessions (Session 1: n = 303, Session 2: n = 224) on measures of substance use before (within 3 hr)/during participation, data quality, demand in hypothetical purchase tasks, delay discounting, and craving. Substance use before/during participation was common (35.7%). Some participants reported substance use before/during both (25.4%) or only one (20.1%) of the sessions. Between-subject analyses of the first session data revealed that participants who used substances before/during participation did not differ on quality measures yet were slower to complete the survey. Controlling for individual differences in demographic variables and typical substance use, using a substance before/during participation was associated with increased hypothetical consumption of substances when the substance was free (demand intensity) and higher craving for substances, but not delay discounting. Substance use before/during MTurk participation among individuals who regularly use substances is prevalent and may impact outcome measures or standardization across sessions in repeated measures designs. Several implications have emerged, including statistically or experimentally controlling for substance use occurring before/during participation, which could improve the validity and rigor of online substance use research, and should be considered a part of best practices. (PsycInfo Database Record (c) 2025 APA, all rights reserved).