Definition
Plain language
A number that says how surprising a result would be if nothing real were going on — small means the result probably isn't just luck.
As stated in the literature
The probability of observing a test statistic at least as extreme as the one measured under the null hypothesis; small values are taken as evidence against the null, with conventional thresholds like 0.05.
Also called: p value
Why it matters: It gives researchers a standard way to judge whether a result is likely real or could easily be a fluke of chance.
For example, if flipping a coin 20 times gives 18 heads, the p-value tells you how unlikely that lopsided result would be from a perfectly fair coin.
Heard on the show
“The correlation is suggestive, the most conservative test the authors run yields a p-value around zero-point-zero-three, so it's significant but not overwhelming.”Episode 015 — The Audit Number Isn't What You Think: Sycophancy and the Case Against Single-Prompt Bias Tests