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Updated: Jul 1, 2026

The Replica Set Method: A High-throughput Approach to Quantitatively Measure Caenorhabditis elegans Lifespan
Published on: June 29, 2018
P-curve won't do your laundry, but it will distinguish replicable from non-replicable findings in observational
Uri Simonsohn1, Leif D Nelson2, Joseph P Simmons3
1Behavioral Science, ESADE Business School, Ramon Llull University, Barcelona, Spain.
Abstract:
p-curve, the distribution of significant p-values, can be analyzed to assess if the findings have evidential value, whether p-hacking and file-drawering can be ruled out as the sole explanations for them. Bruns and Ioannidis (2016) have proposed p-curve cannot examine evidential value with observational data. Their discussion confuses false-positive findings with confounded ones, failing to distinguish correlation from causation. We demonstrate this important distinction by showing that a confounded but real, hence replicable association, gun ownership and number of sexual partners, leads to a right-skewed p-curve, while a false-positive one, respondent ID number and trust in the supreme court, leads to a flat p-curve. P-curve can distinguish between replicable and non-replicable findings. The observational nature of the data is not consequential.
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