Donaldson R F P-Value Calculator
Calculate the p-value from a Z-score, for a one-tailed or two-tailed test.
Uses the standard normal distribution (Z-test). If your sample size is small (under ~30) and you're working from a sample standard deviation, a t-distribution p-value would be more precise — this calculator assumes a large-sample / known-variance Z-test, the most common textbook case.