The p-value of a finding is the probability that the finding would have occurred by chance alone even if the null hypothesis is true.
The following example in the form of a quiz may help clarify the definition.
If you were to conduct an experiment in which you asked both men and women to identify foods by smell, and found that women performed better, and after conducting a t-test, found that p<.05, what would this mean? [Note: These data are fictitious]
- There is at least a 95% chance that, in the entire population, women are better at identifying food by smell than men are.
- In the sample, fewer than 5% of the men performed better than the average woman at identifying foods by smell.
- If men and women were equally good at identifying food by smell, you'd see women doing this much better by chance less than 5% of the time.
- The difference between men and women observed in sample is within 5% of entire population.
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