Hi, everyone, and welcome to module nine.
This module starts our discussion of effect modification,
which you may have heard called interaction or moderation.
You'll hear those terms used interchangeably
throughout this class and in the field of public health.
We've actually been talking about
threats to internal validity way back since module five.
We started out with bias,
then we spent three modules talking about confounding,
and now we're going to spend the next three modules
talking about effect modification using the same structure.
We'll start here in module nine going over the theoretical
and conceptual framework of effect modification.
In the next module, we'll extend that into SPSS
and the statistical techniques
that you use to evaluate effect modification.
Then in module 11, we'll look at interpreting the results
of effect modification in the public health literature.
Effect modification and confounding are similar in concept,
but they're actually very different in practice.
It's a very good idea to read the section
on interaction from your Epi 1 textbook,
"Gordis Epidemiology," before you get into
your current text.
As always, please reach out if you have any questions.
We'll see you in the next module, take care.