A pilot study, pilot project or pilot experiment is a small-scale preliminary study conducted to evaluate the feasibility, duration, cost, constraints, and improve the study design prior to the development of a full-scale research project.[1]​ Pilot studies, therefore, may not be appropriate for case studies.

Pilot experiments are frequently executed prior to a large-scale quantitative search, in order to avoid wasting time and money on an inadequately designed project. A pilot study is usually carried out on members of the relevant population, but not on those who will be part of the final sample. This is because it can influence the late behavior of search topics if they have already been involved in the search.[2]​[3]​[4]​.

A pilot study/experiment is often used to test the large-scale experiment design which can then be modified. It is a potentially valuable idea and in case something is missing from the pilot study, it can be added to the large-scale (and more expensive) experiment to improve the chances of a clear result.

In sociology, pilot studies can be called smaller-scale studies that will help identify design issues before the main search is done.

Although pilot experiments have a strong tradition in public action, their usefulness as a strategy for change has been questioned, at least in the field of environmental management.[5] It is debated that the extrapolation of a pilot study to a large-scale environmental strategy cannot be thought of as possible, in part due to the exceptional resources and favorable conditions that often accompany a pilot study.