Math: What is P-Value
1 - A Grug Example
- Suppose we have a weight-decreasing drug. Is it useful?
- Test on 10 people in three months and collect the mean weight loss, x_bar = -10.
- Say not useful, then 10 people’s weight change follow a natural normal distribution.
- How likely is -10 to occur on the null distribution? If unlikely, null distribution is false.
2 - e-value
- Only need expectation of e is 1. No need null distribution.
- P-value needs P(p < mu) < mu. But e-value doesn’t.