Abstract
J. Cell. Biol. 219 (2020) e202001064 The cell biology literature is littered with erroneously tiny P values, often
the result of evaluating individual cells as independent samples. Because
readers use P values and error bars to infer whether a reported difference
would likely recur if the experiment were repeated, the sample size N used for
statistical tests should actually be the number of times an experiment is
performed, not the number of cells (or subcellular structures) analyzed across
all experiments. P values calculated using the number of cells do not reflect
the reproducibility of the result and are thus highly misleading. To help
authors avoid this mistake, we provide examples and practical tutorials for
creating figures that communicate both the cell-level variability and the
experimental reproducibility.