Himanshu Tripathi Suppose you go to a doctor to check whether you have diabetes or not. Let’s say, H0(Null Hypothesis)= You have diabetes and, H1(Alternative Hypothesis)= You don’t have diabetes.

The doctor could make 2 types of mistake:
1) Type I Error: The doctor says you don’t have diabetes, while in reality, you have it. This is a “serious error” because you might go untreated for a disease you have. This also means that the null hypothesis which is true has been rejected.
2) Type II Error: The doctor says you have diabetes, while in reality, you don’t have it. This means that a false null hypothesis has been accepted.

The probability of making this Type I Error is the level of significance or α.