Why does it matter if a study is labeled a “pilot”?
SHORT ANSWER: …Because a pilot is about testing research methods,….not about answering research questions.
If a project has “pilot” in the title, then you as a reader should expect a study that examines whether certain research methods work (methodologic research). Methods include things like timing of data collection, sampling strategies, length of questionnaire, and so on. Pilots suggest what methods will effectively to answer researchers’ questions. Advance prep in methods makes for a smooth research landing.
Small sample = Pilot? A PILOT is related to study goals and design–not sample size. Of course pilots typically have small samples, but a small sample does not a pilot study make. Sometimes journals may tempt a researcher to call their study a pilot because of small samples. Don’t go there. Doing so means after-the-fact, posthoc changes that were Not the original, a priori goals and design.
Practical problems? If researchers label a study a “pilot” after it is completed (post hoc), they raise practical & ethical issues. At a practical level, researchers must create feasibility questions & answers. (See NIH.) The authors should drop data analysis that answers their original research questions.
Ethics? This ethically requires researchers 1) to say they planned something that they didn’t or 2) to take additional action. Additional action may be complete transparency about the change and seeking modification to original human subjects’ committee approvals. An example of one human subjects issue is that you informed your subjects that their data would answer a particular research question, and now you want to use their data to answer something else–methods questions!
Options? You can just learn from your small study and go for a bigger one, including improving methods. Some journals will consider publication of innovative studies even when small.
Look first, then leap: Better to look a priori, before leaping. If you think you might have trouble with your methods, design a pilot. If you made the unpleasant discovery that your methods didn’t work as you hoped, you can 1) disseminate your results anyway or 2) rethink ethical and practical issues.
Who’s with me? The National Institutes of Health agree: https://nccih.nih.gov/grants/whatnccihfunds/pilot_studies . NIH notes that common misuses of “pilots” are determining safety, efficacy of intervention, and effect size.
Who disagrees? McGrath argues that clinical pilots MAY test safety and efficacy, as well as feasibility. (See McGrath, J. M. (2013). Not all studies with small samples are pilot studies, Journal of Perinatal & Neonatal Nursing, 27(4): 281-283. doi: 10.1097/01.JPN.0000437186.01731.bc )