In a 2017 study, researchers investigated the effect of dietary improvement on adults with moderate to severe depression (Jacka et al. 2017). Subjects were randomly assigned to a treatment group consisting of seven individual nutritional consulting sessions with a clinical dietician or a control condition consisting of a social support protocol with the same visit schedule and length as the treatment group. There were 33 subjects in the treatment group and 34 subjects in the control group. Remission from depression symptoms was achieved by 10 subjects in the treatment group and 2 subjects in the control group.

a. Was this an observational study or a controlled experiment? Explain.

b. Find the percentage in each group that achieved remission from depression symptoms.

c. Researchers performed a test to determine if there was significant difference in outcomes between the treatment and control groups. The p-value for the test is 0.028. Based on a 0.05 significance level, choose the correct conclusion:

i. Researchers have shown that dietary improvement may be an effective treatment strategy for patients with moderate to severe depression.

ii. Researchers have not shown that dietary improvement may be an effective treatment strategy for patients with moderate to severe depression.