Because it is usually not possible to include the entire population in a study, researchers must find a way to recruit some people from the population into their study-the participants who become the sample. The goal of any sampling method is to recruit a representative sample that is the same as the population in every way, except with fewer individuals, but recruitment is costly, resource intensive, and challenging in lots of ways. Representativeness is never perfect, which can lead to selection bias. It is important to remember that generalizability is a continuum; study findings are not a dichotomy of "generalizable" or "not," but, rather, more or less generalizable. J Orthop Sports Phys Ther 2020;50(12):725-726. doi:10.2519/jospt.2020.0704.
Keywords: evidence-based practice; research; sampling.