What does a p-value represent?

What does a p-value represent?

• A. Probability of observing data as extreme as observed if the alternative hypothesis is true.
• B. Probability that the null hypothesis is true given the data.
• C. Probability of observing data as extreme as observed under the null hypothesis.
• D. The observed effect being statistically significant.

Answer: (C)

The p-value tells you how compatible your observed data are with the assumption that there is no real effect (the null hypothesis is true). It’s the probability of getting data as extreme as what you actually observed, or even more extreme, if the null hypothesis holds. This helps gauge whether the observed result would be surprising under no effect. It does not tell you the probability that the null is true given the data, nor does it depend on the alternative hypothesis in that same direct way. It also isn’t the statement that the result is significant by itself; significance comes from comparing the p-value to a chosen threshold (alpha).

The p-value tells you how compatible your observed data are with the assumption that there is no real effect (the null hypothesis is true). It’s the probability of getting data as extreme as what you actually observed, or even more extreme, if the null hypothesis holds. This helps gauge whether the observed result would be surprising under no effect. It does not tell you the probability that the null is true given the data, nor does it depend on the alternative hypothesis in that same direct way. It also isn’t the statement that the result is significant by itself; significance comes from comparing the p-value to a chosen threshold (alpha).