Question

Define "Power" in relation to hypothesis testing.

Answer 1

Definition of power

The probability of not committing a Type II error is called the power of a hypothesis test.

Let me explain it

Power is the probability of rejecting the false null hypothesis .

Therefore if the power of the test is large ( closed to 1) then the chances of making Type II error is small. For example If we want to test the claim that the average mileage of a particular car is greater than 22 km per liter of petrol.

In this case the null hypothesis is, "the  average mileage of a particular car is less than or equal to 22 km per liter of petrol.

So the probability of rejecting null hypothesis which is actually not true is called power.