Welcome to module nine.
This module starts our discussion of effect modification,
which you may also have heard
called interaction or moderation.
And you will really hear those terms used interchangeably
throughout this class
and in the field of public health.
If we take a step back,
we've been talking about threats to internal validity
and epi studies since way back in module five.
We started out with bias
then we spent three modules talking about confounding.
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.
And 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.
I recommend that you go back
and review your epi one notes
just to make sure that you feel solid
about that basic difference.
I've included the chapter from your epi one gorgeous text
on the interaction for reading
before you get into your current text
because I think it will reinforce that solid grounding
before you take a deeper dive into the details
and the analysis piece in the current book.
As always,
please reach out to me or your TA with questions.
And we'll see you in the next module.