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. Author manuscript; available in PMC: 2022 Feb 1.
Published in final edited form as: Exp Physiol. 2020 Dec 8;106(2):375–376. doi: 10.1113/EP089142

Figure 1. A randomly-generated dataset illustrating a statistically inappropriate secondary analysis that is commonly encountered in the literature.

Figure 1.

Panel A includes mean (top) and individual (bottom) data for all individuals (n=100). No significant differences in variable Y in response to treatment X were noted by paired t-test (p=0.92). Panel B includes mean (top) and individual (bottom) data for individuals with lowest Y levels at baseline (n=50). A significant effect of treatment X was noted by paired t-test (p<0.01). Error bars in top sub-panels denote standard deviation. Data were randomly generating using the Excel function [=RANDBETWEEN(0,100)]. The analysis presented in panel B lead to the erroneous conclusion that treatment X increases Y in individuals with low levels of Y at baseline.