A researcher investigates if chocolate affects mood She recr

A researcher investigates if chocolate affects mood. She recruits college students to take a mood inventory, ingest a quarter pound of chocolate and then complete the mood inventory again. Given the following confidence interval [2.34, 5.41], make a decision about the hypotheses.

Question 5 options:

Reject the null hypothesis and conclude that chocolate affected mood because zero, or no effect, does not fall within the confidence interval.

Reject the null hypothesis and conclude chocolate lowers affect because the confidence interval includes small numbers.

Fail to reject the null hypothesis because the confidence interval is positive.

Fail to reject the null hypothesis and conclude the effect size is small for this study.

Solution

Answer: Reject the null hypothesis and conclude that chocolate affected mood because zero, or no effect, does not fall within the confidence interval.

Reason: Results for hypothesis testing can be derived using confidence intervals. A null hypothesis setting the slope to be zero is rejected if the confidence interval of the slope parameter does not include zero, like in this case.