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Intervention Fidelity in Research

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Intervention Fidelity in Research answers the question “Was the intervention delivered as intended?” It’s a measure of how close to what was planned an intervention or experiment ended up being in practice.

An intervention is some form of treatment, but it could also be a specified active or non-active non-treatment. For example, a placebo is an inert intervention; Treatment as Usual (TUA) can be a very active intervention.

Intervention fidelity is especially important in determining the place an experiment or study might have in a larger study, and whether the results can be replicated or generalized.

Determining Intervention Fidelity in Research

To assess fidelity, the intervention’s reliability and validity must be assessed using appropriate methods.

There is no one statistic or measurement technique that is used to determine intervention fidelity everywhere. Researchers involved in a multi-faceted project, though, often work to put together a project-specific rubric by which the fidelity of all related experiments or intervention can be judged.

Sometimes a survey, given to either researcher or the intervention subject, is used to determine intervention fidelity. Sometimes assessments are conducted within and after an intervention to check just how closely a researcher is following the specified procedure; or a team of experts is asked to do spot checks on interventions in progress.

The key is that the intervention be well defined beforehand, and areas in which it is important to stick to the book as well as those in which some latitude for change may be given are specified in advance.


Taylor, Weston, & Batterham. Evaluating Intervention Fidelity: An Example from a High-Intensity Interval Training Study. April 22, 2015 PLOS ONE 10(4): e0125166. Retrieved from on August 10, 2018.

CanChild. Ensuring Intervention Fidelity in Rehabilitation Research. Retrieved from on August 10, 2018.

Cordray. Assessing Intervention Fidelity in Randomized Field Experiments. Retrieved from on August 10, 2018.

Murphy & Gutman. Intervention Fidelity: A Necessary Aspect of Intervention Effectiveness Studies. American Journal of Occupational Therapy, July/August 2012, Vol. 66, 387-388. doi:10.5014/ajot.2010.005405. Retrieved from on August 10, 2018.

Mowbray, Holter, Teague, & Bybee. Fidelity Criteria: Development, Measurement, and Validation. American Journal of Evaluation, Vol 24, Issue 3, pp. 315 – 340. Retrieved from on August 10, 2018.

Bellg, A. J., Borrelli, B., Resnick, B., Hecht, J., Minicucci, D. S., Ory, al. .; Treatment Fidelity Workgroup of the NIH Behavior Change Consortium., (2004). Enhancing treatment fidelity in health behavior change studies: Best practices and recommendations from the NIH Behavior Change Consortium. Health Psychology, 23, 443–451.
Gearing, R. E., El-Bassel, N., Ghesquiere, A., Baldwin, S., Gillies, J., & Ngeow, E. (2011). Major ingredients of fidelity: A review and scientific guide to improving quality of intervention research implementation. Clinical Psychology Review, 31, 79–88.


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