To understand whether the result is a Type I error, a Type II error, or a correct decision, let’s first clarify each term:
- Type I Error: This occurs when the null hypothesis is rejected when it is actually true.
- Type II Error: This occurs when the null hypothesis is not rejected when it is actually false.
- Correct Decision: This occurs when the null hypothesis is rejected (or not rejected) correctly based on the true state of the hypothesis.
In your scenario:
- The null hypothesis \( H_0: \mu = 1 \) is rejected based on the P-value of 0.03.
- The true value of \( \mu \) is 4.
Since you rejected the null hypothesis \( H_0 \) (which is true according to your rejection decision), and the true value of \( \mu \) is indeed different from 1 (it is 4), your decision to reject \( H_0 \) is actually correct because the null hypothesis is false.
Therefore, since you correctly rejected a false null hypothesis, the result is a correct decision.
So the answer to your question is: