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 well the results of an intervention or experiment matched up to what was actually planned.

intervention fidelity
Intervention fidelity measures how well the treatments were delivered.
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 isn’t a universal statistic or test 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. The choice of statistic or test then, often boils down to what experts, colleagues, or superiors deem suitable.

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 should be well defined beforehand. This should include areas where it’s important to stick to the book, as well as those where some leeway is possible are specified in advance.


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.

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.

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.

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.

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.

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