Below are results from a case-control study of physical inactivity and the risk of coronary heart disease (CHD). There were 500 participants in the study.

	CHD	Controls	Total
No exercise	127	110	237
Exercise	73	190	263
	200	300	500

The study researchers were concerned that diet may affect the association between physical activity and CHD, so they divided the study participants by whether or not they ate a high fat diet. Here are the results:

Moderate/high fat diet

	CHD	Controls	Total
No Exercise	114	60	174
Exercise	33	20	53
	147	80	227

Low fat diet

	CHD	Controls	Total
No Exercise	13	50	63
Exercise	40	170	210
	53	220	273

1. The crude (overall) odds-ratio is

Group of answer choices

A. 3.0

B. 1.11

C. 1.05

D. 0.91

E. 2.03

F. 1.15

2. The stratum-specific odds-ratio for moderate/high fat diet group is

Group of answer choices

A. 1.15

B. 0.91

C. 1.11

D. 3.0

E. 2.03

F. 1.05

3. The stratum-specific odds-ratio for low fat diet is

Group of answer choices

A. 2.03

B. 0.91

C. 1.15

D. 3.0

E. 1.11

F. 1.05

4. Based on the stratum-specific odds ratios you calculated, what do you conclude?

Group of answer choices

A. There is some association between exercise and CHD, but it is confounded by diet.

B. There is no association between diet and CHD.

C, There is some association between exercise and CHD, but it is modified by diet.

D. There is no association between exercise and CHD

E. The investigator did not need to stratify the data by diet.

5. A confidence interval for the stratum-specific odds-ratio for the association between physical activity and CHD in those with a high-fat/moderate diet is calculated as (0.90-1.70). This best interpretation of this is:

Group of answer choices

A. There is a statistically significant positive association between exercise and CHD in those who consume a high/moderate fat diet

B. Diet is not associated with physical activity

C. There is not a statistically significant association between exercise and CHD in those who consume a high fat/moderate diet

D. There is not a statistically significant association between diet and CHD in people who exercise

E. Diet is an effect modifier