Responsible product design to mitigate excessive gambling: A scoping review and z-curve analysis of replicability

Objectives: Systematic mapping of evaluations of tools and interventions that are intended to mitigate risks for gambling harm. Design: Scoping Review and z-curve analysis (which estimates the average replicability of a body of literature). Search strategy: We searched 7 databases. We also examined reference lists of included studies, as well as papers that cited included studies. Included studies described a quantitative empirical assessment of a game-based (i.e., intrinsic to a specific gambling product) structural feature, user-directed tool, or regulatory initiative to promote responsible gambling. At least two research assistants independently performed screening and extracted study characteristics (e.g., study design and sample size). One author extracted statistics for the z-curve analysis. Results: 86 studies met inclusion criteria. No tools or interventions had unambiguous evidence of efficacy, but some show promise, such as within-session breaks in play. Pre-registration of research hypotheses, methods, and analytic plans was absent until 2019, reflecting a recent embracement of open science practices. Published studies also inconsistently reported effect sizes and power analyses. The results of z-curve provide some evidence of publication bias, and suggest that the replicability of the responsible product design literature is uncertain but could be low. Conclusion: Greater transparency and precision are paramount to improving the evidence base for responsible product design to mitigate gambling-related harm.