1. Actor-Partner Interdependence Model or APIM David A
Actor-Partner Interdependence Model or APIM David A. Kenny University of Connecticut

2. APIM
A model that simultaneously estimates the effects one's own characteristics and one's partner's characteristics on an outcome variable
Data Requirements
two variables, X and Y, and X causes or predicts Y
Both members of the dyad have scores on X and Y

3. Actor Effect
Definition: The effect of a person’s X variable on that person’s Y variable
Example: the effect of one's depression on one's quality of life
Both members of the dyad have an actor effect

4. Partner Effect
Definition: The effect of a person’s partner’s X variable on the person’s Y variable
Example: the effect of partner's depression on quality of life
Both members of the dyad have a partner effect

5. APIM Diagram Person 1's Depression Person 1's Quality of Life
Actor for Person 1
Person 1's
Quality of Life
Partner from 2 to 1
Partner from 1 to 2
Person 2's
Depression
Person 2's
Quality of Life
Actor for Person 2
The partner effect is fundamentally dyadic, but a common convention is to refer to it by the outcome variable. So "Partner from 2 to 1" would be called the "partner effect for person 1."

6. The APIM and Health Research
Consider romantic couples
Each member either diagnosed (D) or undiagnosed (U)
Four major designs DU UU DD
UU, DU, and DD

7. DU Studies: Some Examples
Kim et al. (2008): the influence of psychological stress on life quality among mothers with cancer and their adult care giving daughters
Hong et al. (2005): the association between the provision and receipt of social support in cardiac patients and their spouses  
Mellon et al. (2007): factors associated with the fear of cancer-recurrence in cancer survivors and their caregivers
Kershaw et al. (2008): effect of stress on coping in prostate cancer patients and their spouses
Dorros et al. (2010): effect of depression on health in women with breast cancer and their partners

8. Key Questions in DU Studies
Almost always there are mean differences on Y between D and U, but also important are differences in actor effects and especially between partner effects, i.e., measuring bidirectional influence.
Important to test for asymmetry in:
Y intercepts
Actor effects
Partner effects
Error variances in Y

9. UU Studies Health Promotion Studies Some Examples Key question
Dickerson & Kemeny (2004): effect of stress on cortisol levels
Klumb et al. (2006): effect of housework on cortisol levels
Butterfield & Lewis (2002): effect of tactics on health-related behaviors
Key question
Presence of partner effects

10. DD Studies
Example: Knoll et al. (2009): Effects of stress on depression in couples undergoing assisted reproduction treatment.
Key question: Partner effects
Study would benefit by having a UU control group to see if effects are stronger or weaker in DD vs. UU couples.

11. UU, DU, and DD Studies Some Examples Key questions
Hoff et al. (2009) conducted studies of gay men in which one, both, or neither member was HIV positive.
McMahon et al. (2007) studied gay men where one member, both members, or neither member was diagnosed with hepatitis C.
Key questions
What is the effect of Disease on the behaviors and perceptions of person and their partner.
Couple type as a moderator

12. Not Discussed Distinguishability Statistical estimation of the APIM
Actor-partner interactions
Over time studies
Alternative dyadic models

13. APIM Work in Progress
Testing Patterns Using k (Kenny & Lederman, 2010; Journal of Family Psychology)
Mediation (Lederman, Macho, & Kenny, 2011; Structural Equation Modeling)
Common Fate Model as an Alternative to the APIM (Lederman, & Kenny, under editorial review)
Moderation (Garcia, Lederman, & Kenny, in preparation)

14. Thank You!