Objective:

To describe the basic elements of the pilot studies, their purpose and their evaluation components.

Development:

Health interventions are generally developed in four phases. This article focuses on the Second Phase, which corresponds to pilot studies. Generally speaking, pilot studies are designed and implemented to analyze the fidelity, acceptability, and preliminary effects of an intervention. Fidelity refers to the relationship between the intervention's active ingredients and its components and activities (theoretical), and the degree to which the intervention is delivered according to what was planned (operational). Acceptability includes the participant's satisfaction towards the intervention and the interventionist. Preliminary effects refer to the ability of the intervention to induce changes in the outcome of an intervention.

Conclusions:

A Pilot Study is one of the first steps in an intervention project. A pilot study allows informed decisions to be made about the implementation of a larger research project. This article intends to serve as a guide for the design, implementation and evaluation of pilot studies.