A multi-state methodological framework for behavioral surveillance of cannabis-impaired driving

Driving under the influence of cannabis is a growing public health concern in the United States. Existing surveillance systems often lack behavioral detail, rely on static quotas, or fail to account for differences across legal contexts. The Cannabis and Roadway Safety Study (CARSS) is a multi-phase project designed to address these gaps. This paper describes the methods of the Phase 2 questionnaire.

A cross-sectional, mixed-methods questionnaire assessed cannabis use patterns, driving behaviors, impairment beliefs, and messaging preferences among adult drivers who currently use cannabis. The study employed a structured online questionnaire incorporating quantitative items and AI-assisted qualitative probes. Screening, quota sampling, and rake weighting were used to achieve state-level demographic representation based on 2020 U.S. Census benchmarks, with real-time monitoring. A secondary weighting step aligned full questionnaire participants with adult drivers who currently use cannabis within each state.

The framework was implemented across eight U.S. states representing non-medical, medical-only, and prohibition policy environments, with data collection from November 28, 2023, to February 13, 2024. All states achieved target sample sizes of approximately 250 respondents, yielding a total analytic sample of 2,023 participants. Recruitment dynamics varied by state, with some requiring extended fielding to meet demographic targets. Usable open-text responses were obtained in all states through AI-assisted probing across policy environments.

CARSS Phase 2 demonstrates the feasibility of integrating responsive quota monitoring, multi-step weighting, and AI-assisted qualitative probing into a scalable, multi-state surveillance framework for cannabis-impaired driving research and related public health.