Sampling > Critical Case Sampling
What is Critical Case Sampling?
Critical case sampling is where you collect samples that are most likely to give you the information you’re looking for; They are particularly important cases or ones that highlight vital information.
This type of sampling is “…particularly useful if a small number of cases can be sampled” (Strewig & Stead, 2001). That small number of cases (assuming they can be classified as “critical”) are the ones more likely to provide a wealth of information.
Why Use Critical Case Sampling?
As Patton (1990) states: “If it can happen there, it can happen anywhere.” Let’s say you were studying reading levels for a popular science magazine, with reading levels ranging from an 8th grade level all the way up to graduate school. If 8th graders can understand the science articles, then everyone about that level should also be able to understand the articles — making the 8th grade level readers a “critical case.” Using critical cases also makes sense if you’re on a tight budget and want to study the participants who are most likely to provide crucial information.
Scientists deal with critical cases all of the time. For example, Gregor Mendel discovered the fundamental laws of inheritance through his meticulous study of pea plants. If Mendel had attempted to focus on a broad range of species instead of just one, he may not have made the discoveries that he is renowned for, such as his finding that genes are inherited in pairs — one from each parent.
Cold Spring Harbor Laboratory. DNA Learning Center: Gregor Mendel. Retrieved 1/20/2017 from: https://www.dnalc.org/view/16151-biography-1-gregor-mendel-1822-1884-.html
Patton, M. (1990). Qualitative evaluation and research methods. Beverly Hills, CA: Sage. PDF.
Strewig, F. & Stead, G. (2001) Planning, Reporting & Designing Research. Pearson, South Africa.