I am wondering whether you meant negative multiplicative interaction and positive additive interaction rather than positive multiplicative interaction and negative additive interaction?
VanderWeele talks about negative multiplicative interaction and positive
additive interaction in his article and not the other way around.
Hi Sandeep,
We are asking you for negative multiplicative interaction and positive additive interaction. If you like you could answer positive multiplicative interaction and negative additive interaction. We can compare both answers in class. For these questions, consider how you can use the RERI definitions (part 3 slide 12) and definition of multiplicative interaction (Part 3 slide 7) to help come up with different scenarios.
Thank you for your question.
"Find values for the stratum-specific relative risks (RR10, RR01, RR11) where you have positive multiplicative interaction and negative additive interaction. As above, assume RR00=1 (reference). Numeric answers will vary; show your work. (2 pt)"
I think Monica may have reversed her terms, accidentally. Regardless, I believe the HW question is correct as written. Her point is that you may come up with values for the situation you described as well, if you prefer and we can discuss in class. The purpose of this question is to go thru the process of applying what we know about interaction summary metrics to see how these can be applied to different scenarios, and what patterns one can discern. We were not focused specifically on scenarios from any particular reading. The one you describe is an appropriate scenario to consider as well, though.
Best,
JMC
