Modeling synergy: How to assess a Type D personality effect

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Abstract

Objective
In research on Type D personality, its subcomponents negative affectivity (NA) and social inhibition (SI) are hypothesized to have a synergistic effect on various medical and psychosocial outcomes. As some methods to analyze Type D personality have been criticized, this study investigated whether these methods adequately detect a Type D effect.

Method
We used a simulation and two empirical illustrations to investigate each method's performance (bias, power and false positives) in detecting the Type D effect.

Results
Our simulation showed that the two most commonly used methods to assess the Type D effect (subgroup methods) were primarily picking up the presence of NA or SI main effects, indicating that these methods might falsely suggest synergistic Type D effects. Moreover, these methods failed to detect the combined presence of the NA and SI main effects, resulting in significant Type D effects when only one of the NA/SI main effects was present. The method that best detected Type D effects modeled the continuous NA/SI main effects and their statistical interaction in a regression analysis. Reanalysis of two empirical Type D personality datasets confirmed the patterns found in our simulation.

Conclusion
This study showed that Type D effects should be modeled with a continuous interaction approach. Other approaches showed either more bias, more false positive findings or lower power. We recommend against using subgroup approaches to operationalize Type D personality, as these methods are biased, regardless of whether the Type D effect is synergistic or additive in nature.
Original languageEnglish
Article number109990
Number of pages11
JournalJournal of Psychosomatic Research
Volume132
DOIs
Publication statusE-pub ahead of print - 2020

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Keywords

  • ALL-CAUSE MORTALITY
  • CARDIAC EVENTS
  • CORONARY-ARTERY-DISEASE
  • Dichotomization
  • Interaction
  • NEGATIVE AFFECTIVITY
  • OUTCOMES
  • PREDICTIVE-VALUE
  • PROGNOSTIC VALUE
  • PSYCHOLOGICAL DISTRESS
  • SOCIAL INHIBITION
  • Simulation
  • Synergy
  • Type D personality
  • VARIABLES

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