Definitions for "Test statistic"
A random variable that is used to choose between two hypotheses in a hypothesis test. Its distribution under the null hypothesis is known. Its value is calculated from data and its distribution assuming H0 is true is used in the test. Extreme values of the test statistic under H0 lead us to reject the null hypothesis.
a computed quantity used to decide hypothesis tests.
A function of a sample of observations that provides a basis for testing a statistical hypothesis.
A numeric summary value used to determine significance under the decision rule.