The data in Table 4.11 represent the results of a study on risk factors for falls in an elderly population. The data were collected using a retrospective study design. Select the appropriate measure of association, and calculate it for each risk factor (arthritis, heart disease, diabetes, colon cancer, and unstable gait). Use a 2-by-2 contingency table for each risk factor.

Contamination. The hospital administrator decides to conduct a hospital-based study that may show a strong association between unpasteurized milk consumption and salmonella cases in the community. The following information is abstracted from hospital medical records:

• During the past three years, 10% of the community population was hospitalized at least one

• A review of admission forms indicates that of 15,000 admitted patients, 64 were admitted for salmonella infections.

• A total of 3,487 of the 15,000 admitted patients reported that they had consumed unpasteurized milk.

• Thirteen of the patients who reported that they had consumed unpasteurized milk were admitted for salmonella infections.

a. What study design should the hospital administrator select? Why?

b. Calculate the appropriate measure of association.

c. What can be concluded from this hospital-based study with respect to the association of consuming unpasteurized milk and salmonella infection?

Q8

Discuss the characteristics, strengths, and weaknesses of the following study designs:

a. Cross-sectional

b. Retrospective

c. Descriptive

d. Prospective

Describe an ecologic study, present its strengths and weaknesses, and give an example.