Reflections on the measurement of implementation constructs.

To advance research and practice, it is crucial to build on validated measures. A wide range of measures for implementation research were identified in seven systematic reviews conducted under the auspices of the project, "Advancing Implementation Science through Measure Development and Evaluation," but many had unclear or limited measurement qualities. In this commentary, I suggest the psychometric paradigm of measurement validation may have to be reconsidered because many determinants and outcomes of interest are defined at higher levels of aggregation than the individual. Nonetheless, the practice of using non-validated measures should be reduced, and measurement validation research should be encouraged. Adaptation of existing measures to different domains, settings, and languages further adds to the need for validation research. Coordination of the development and validation of measures is required to avoid unneeded replication in some domains and lack of measures in others, and to take care that validation research remains instrumental to the purposes of implementation research and practice. Plain language abstract: Many measures for implementation research have limited or unknown qualities. There is thus a need for better measures and targeted research is required to provide those. New studies should use measures of high-quality whenever possible.