The leader of two postpartum women’s support groups is interested in the depression levels of the women in her groups. She administers the Center for Epidemiologic Studies Depression Scale (CES-D) screening test to the members of her groups. The CES-D is a 20-question self-test that measures depressive feelings and behaviors during the previous week.
The mean depression level from the screening test for the 8 women in the first group is μ₁ = 14; the mean depression level for the 12 women in the second group is μ₂ = 12.
Without calculating the weighted mean for the combined group, you know that the weighted mean is:

Midway between 14 and 12
Closer to 14 than to 12
Closer to 12 than to 14
Compute the weighted mean. Enter your answer rounded to one decimal place.
μ =
The support group leader realizes that she should also screen for alcohol abuse, so she gives the women in her two groups the Michigan Alcohol Screening Test (MAST). The MAST is a 22-question self-test focusing on the use and abuse of alcohol.
The first group has a mean score of μ₁ = 16. The second group has a mean score of μ₂ = 12.
Compute the weighted mean. Enter your answer rounded to one decimal place.
μ =

Respuesta :

For the depression level screening test:

Group 1:

- Number of women: 8

- Mean depression level: 14

Group 2:

- Number of women: 12

- Mean depression level: 12

To compute the weighted mean:

μ = (8 × 14 + 12 × 12) ÷ (8 + 12)

μ = (112 + 144) ÷ 20

μ = 256 ÷ 20

μ = 12.8

So, the weighted mean for the depression level screening test is 12.8.

For the alcohol abuse screening test:

Group 1:

- Number of women: 8

- Mean alcohol abuse score: 16

Group 2:

- Number of women: 12

- Mean alcohol abuse score: 12

Using the same formula:

μ = (8 × 16 + 12 × 12) ÷ (8 + 12)

μ = (128 + 144) ÷ 20

μ = 272 ÷ 20

μ = 13.6

So, the weighted mean for the alcohol abuse screening test is 13.6.