Is the Data Dirty or Clean?
The Role of Experimental Design in Human Health Studies
School of Medicine
University of California, San Francisco
This case study challenges students to differentiate between anecdotal evidence and science-based evidence related to human health. The case uses a "flipped" approach in which students watch two preparatory videos prior to attending class. The first video defines anecdotal evidence while the second characterizes the different categories of scientific studies that generate evidence that is not anecdotal. Students watch the videos, analyze scenarios for anecdotal evidence, and think about what types of evidence they use to make health-related decisions. When students meet in class, they work in groups to compare and contrast these different categories of scientific studies and classify actual research studies aided by a dichotomous key for distinguishing between different types of studies related to human health. Primarily designed for students in introductory general biology courses, the activity could also be useful for lower division nutrition, physiology, or non-major biology courses or any course where students need to differentiate between science and pseudoscience.
- Identify differences between pseudoscience and scientific evidence.
- Classify experimental design approaches in studies involving human health.
- Evaluate the credibility of evidence from various types of human studies.
Keywordsclinical trial; human subjects; epidemiological studies; scientific method; intervention; observation; correlation vs. causation; placebo; pseudoscience; anecdotal evidence; evidence-based medicine
Topical AreasScientific method, Pseudoscience
Educational LevelHigh school, Undergraduate lower division, Undergraduate upper division, General public & informal education
Type / MethodsDiscussion, Flipped, Jig-Saw
Subject HeadingsBiology (General) | Medicine (General) | Public Health | Statistics | Nutrition | Science (General) |
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The following video(s) are recommended for use in association with this case study.
- What is Pseudoscience?
This video introduces pseudoscience as a science mimic that lacks empirical facts and procedures. The birth of Spiritualism from the Fox sisters’ hoax is briefly described. Running time: 3:53 min. Produced by Objective: Change the World, 2015.
This video gives an overwiew of the distinction between “clean” and “dirty” data and argues that the plural of “anecdote” is not “data.” The narrator examines various scenarios involving Reiki healing to highlight the risks associated with anecdotal evidence as it relates to health decisions. Running time: 7:42 min. Produced by Body of Evidence, 2016.
- Categories of Experimental Design Applicable to Human Health
Not all evidence is equal; there are differences in validity, credibility, and the ability to make direct applications to human health. Some of these differences come from the way data is collected or experimental design. This video identifies the main categories of experimental design that apply to human health. Running time: 6:32 min. Created by Chantilly A. Apollon for the National Center for Case Study Teaching in Science, 2017.