Mediation and Moderation Flashcards
What is the difference between moderation and effect modification?
Same concepts.
Interaction refers to statistical method to test.
What is difference between mediator and confounder?
Mediator and confounder both related to exposure and outcomes of interest but mediator IS on causal pathway and confounder IS NOT on causal pathway.
What is major entity in a study?
Unit of analysis that is being analyzed in a study.
What you are attempting to study.
What is unit of observation?
What you actually study/item you actually observe.
Does the RQ focus on unit of analysis or unit of observation?
Unit of observation.
What is the ecological fallacy?
Observed characteristic of a group leads to inference about individual members (i.e. incorrectly making conclusions about individuals based on analyses of group data).
What is moderation?
The effect (strength and direction) of the exposure on an outcome depends on the level of a third variable.
How do we test moderation statistically?
Through an interaction term.
This is the cross-product of the moderator and the exposure.
See if slopes are parallel
Can we tell if there is moderation by looking at stratified coefficients?
No. Need interaction term.
How do we know if there is interaction?
P-value needs to be significant.
What is a mediator?
Associated with exposure and outcome and on causal pathway. A mediator account for RL between independent and dependent variable. Has direct and indirect effects.
It is a HYPOTHESIS about a causal netowrk.
What are the steps for interaction?
1) Center any continous predictors
2) Enter main effects
3) Enter interaction terms
4) Test interaction term
5) If significant, plot
What are steps for assessing mediator?
1) Show causal variable associated with outcome
2) Show causal variable associated with mediator
3) Show mediator affects outcome
What is partial mediation?
When partially accounts for RL between exposure and outcome.
What is full mediation?
When RL between exposure and outcome is 0.
