Glossary

Confidence interval

A range built by a procedure that covers the true value in a stated share of repeated samples, usually 95%.

Power

The probability that a test detects an effect of a given size. Plan for at least 0.8.

Effect size

The magnitude of a difference in units that do not depend on the sample size, for example Cohen's d.

p-value

The probability of data at least this extreme if the null hypothesis holds. It is not the probability that the hypothesis is true.

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