Background: Drug policy research is at an important methods crossroads. There has been concern but no explicit consensus about methods for properly measuring exposure to policy – typically the independent variable in any causal inference study of policy effects. Increasing availability of open-source legal data produced using transparent “policy surveillance” methods (such as PDAPS and Rand’s OPTIC data) has been positive, but studies continue to be published that do not use robust methods of legal measurement, or do not provide sufficient detail for assessing and replicated legal measurements.
Objectives: To explicitly set out basic standards for measurement of policy exposure in drug policy research.
Methods: The presentation draws on existing methods literature and the authors’ expertise.
Results: “Policy” for evaluation purposes consists of an observable law or law-like text. Research should objectively measure attributes of the text relevant to the hypothesis being tested, normally including effective date (or other theoretically relevant date such as enactment, signing or implementation), start and end dates of observation, regulated activities/specified standards, persons subject to the law, and penalties. Any categorization (such as “ “stringency”) should be conducted as a secondary operation based on the previously measured features of the text. Data should be public and be accompanied by a code book and detailed protocol describing research and quality control procedures for collecting policy texts and measuring their features.
Implications: Attention to feasible methodological standards can ensure that published drug policy research exhibits transparent, replicable and credible measurement of policy exposure.