A re-evaluation of the Type D personality effect
Below is a short summary of a new study I published in the Personality and Individual Differences. This study is a sequel to my study published in the Journal of Psychosomatic Research, earlier this year. Click here to download the published article
Type D personality has been associated with various medical and psychosocial outcomes. Type D’s underlying personality traits negative affectivity (NA) and social inhibition (SI) are hypothesized to either additively (NA + SI) or synergistically (NA ∗ SI) affect an outcome. As some of the methods used to assess a Type D effect have been criticized in the past, this study aimed to investigate for all commonly used methods their tendency of producing false positive Type D effect. 324,000 datasets were generated using a Monte Carlo Simulation. Each dataset was analyzed using various methods to assess a Type D effect. Each method’s performance was assessed in terms of absolute bias and the percentage of false-positive findings. An online application was developed where readers can easily experiment with this simulation. Our simulation showed that all commonly used methods risk producing false-positive Type D effects. The only method with adequate false-positive rates included the continuous NA and SI main effects, as well as their quadratic effects and their interaction. All commonly used methods to assess a Type D personality effect showed inflated false-positive rates in realistic simulation scenarios. All earlier research based only on these methods should be reconsidered.