UPDATED INSTRUCTIONS for q11, Exam
Please note that we have updated the instructions for q11 below to avoid confusion (new exam version 2a posted on CLE today at 10:38am (3/16), and edits shown below in underline).
11. Consider the 16 Response Types in the epi_207_interaction app. https://francoisrerolle.shinyapps.io/epi_207_interaction_app/
Let smoking be exposure A and taking beta-carotene supplements be exposure E. Your outcome is lung cancer. Your population size is 10,000. Imagine that 25% of people smoke and 30% of people take beta-carotene supplements. Imagine that in the population, there are the following types of people:
- smoking causes lung cancer, and beta-carotene usage has no effect.
- smoking and beta-carotene usage do not cause lung cancer (neither separately nor together), and this type never gets lung cancer (Type 16 Immune)
- smoking and beta-carotene usage do not cause lung cancer (neither separately nor together), and this type always gets lung cancer (Type 1 Doomed)
What response type matches the first description above? Identify the type (by number and description)
Next, give each of these types a weight of 1 in the app. Sample the population.
Comment on the presence of additive and multiplicative interaction, using the Interaction Contrast Risk Difference and Risk Ratio, respectively. Please include a snap shot of your results.
Now imagine that there is the additional type:
- smoking and beta-carotene usage causes lung cancer, but by themselves, neither leads to lung cancer alone
What response type match the description above? Identify the causal type by number.
Next, give this type a weight of 1 in the app. Sample the population.
Comment on the presence of additive and multiplicative interaction, using the Interaction Contrast Risk Difference and Risk Ratio, respectively with this new population mix. What effect would you expect this type to have by itself (assume Doomed and Immune stay in the population, for app stabilization)? Is that effect apparent? Explain briefly. Please include a snap shot of your results.