Question

Vitamin D is important for the metabolism of calcium and exposure to sunshine is an important source of vitamin D. A researcher wanted to determine whether osteoperosis was associated with a lack of exposure to sunshine. He selected a sample of 250 women with osteoperosis and an equal number of women without osteoperosis. The two groups were matched - in other words they were similar in terms of age, diet, occupation, and exercise levels. Histories on exposure to sunshine over the previous twenty years were obtained for all women. The total number of hours that each woman had been exposed to sunshine in the previous twenty years was estimated. The amount of exposure to sunshine was compared for the two groups.

Required:
a. Determine whether this is a controlled experiment or an observational study.
b. Identify the treatment variable.

Answer 1

Vitamin D and Osteoporosis

a. This is an observational study. The researcher is trying to observe the two groups of women who suffer from osteoporosis. She did not apply any treatment on any group, as is the case with experimental researches.

b. The treatment variable is the amount of exposure to sunshine.

Explanation:

This study is an observational research because the researcher lacks the control over the variables, especially the amount of exposure to sunshine. She is merely observing what has occurred previously. On the other hand, an experimental study will involve the application of some treatments to one group of women and then the recording of the effects. But in this case, the researcher merely recorded the effects that had occurred without applying any treatment to any group.