# I need help with Null Hypothesis type 1 and 2 errors

#### johnkims41

##### New Member
Explain which type of error, type 1 or type 2, could be made in each of the following cases. Just pick A, B C or D. For example for (I) Pick one of the four options (A B C or D). For (II) Pick one of the four options (A B C or D) for (III) Pick one of the four options (A B C or D), for (IV) Pick one of the four options (A B C or D). Total of four answers.

What i got: ( Not sure if I'm right though).
I. C
II. A
III. B
IV. D

(I) The null hypothesis is true.

A) Type 1 It would happen if the null hypothesis is rejected
B) Type 1 It would happen if the null hypothesis is true
C) Type 2 It would happen if the null hypothesis is not rejected
D) Type 2 It would happen if the alternative hypothesis is true

(II) The alternative hypothesis is true.

A) Type 1 It would happen if the null hypothesis is rejected
B) Type 1 It would happen if the null hypothesis is true
C) Type 2 It would happen if the null hypothesis is not rejected
D) Type 2 It would happen if the alternative hypothesis is true

(III) The null hypothesis is not rejected.

A) Type 1 It would happen if the null hypothesis is rejected
B) Type 1 It would happen if the null hypothesis is true
C) Type 2 It would happen if the null hypothesis is not rejected
D) Type 2 It would happen if the alternative hypothesis is true

(IV) The null hypothesis is rejected.
A) Type 1 It would happen if the null hypothesis is rejected
B) Type 1 It would happen if the null hypothesis is true
C) Type 2 It would happen if the null hypothesis is not rejected
D) Type 2 It would happen if the alternative hypothesis is true

#### Rhodo

##### New Member
It seems like the definition you're using for Type I and Type II errors is misguiding you.

A type I error may be defined as rejecting H0 when H0 is true, and type II error as failing to reject H0 when H0 is false.

Looking at question 1, if the null hypothesis is true, and you fail to reject the null, as you answered, then you actually wouldn't be making an error at all. You would be making the correct decision in this case. However, if you rejected the null and it was in reality true, this would be an error. I'll leave it to you to decide which type.

Hopefully this helped and will guide you for the remaining questions!