MPH 101 Case Control Studies Questions

Alternate Lab 3 – Case Control Studies

Part A. Selection Group Bias

Please read the hypothetical example below to answer the following questions.

Scenario 1.

Researchers asked the cases to select two close female friends aged 40-60 without breast cancer who would be interested in participating in the study. Out of the 200 best-friend controls, 39 reported moderate alcohol consumption over the past year.

1. Create a 2×2 table using the above information regarding cases and controls.

1. Calculate the OR (Show your work. Round final answer to 2 decimal places)

1. Interpret the OR.

Scenario 2.

Researchers decided to use patients with a different form of cancer to serve as controls. Researchers recruited 200 females (age 40-60) with newly diagnosed liver cancer to serve as controls. Of the 200 controls, 140 reported regular moderate alcohol consumption.

1. Create a 2×2 table using the above information regarding cases and controls.

1. Calculate the OR (Show your work. Round final answer to 2 decimal places)

1. Interpret the OR.

Scenario 3

Researcher used random digit dialing to attempt to randomly recruit women aged 40-60 as controls in the study. Of the 200 controls recruited, 30 reported regular moderate alcohol consumption

1. Create a 2×2 table using the above information regarding cases and controls.

1. Calculate the OR (Show your work. Round final answer to 2 decimal places)

1. Interpret the OR.

Summary Questions

1. Did the odds of exposure in cases (odds of case exposure) change in scenario 1, 2, and 3?

1. Did the odds ratios change in scenario 1, 2, 3? Why or Why not?

1. To optimize validity in this study, which control group would you choose and why?

1. Describe how limitation on recall (remembering) might affect the measurement of exposure in all groups.

1. There is a potential for differential recall (remembering) in case control studies, particularly when choosing healthy controls. Explain how differential recall might be present in scenario 3.

Part B. Yes/No

Please write “yes” or “no” in each cell below to answer the following comparisons between a case-control study and a cross-sectional study