Examining the effects of birth order on personality.
This study examined the long-standing question of whether a person’s position among siblings has a lasting impact on that person’s life course. Empirical research on the relation between birth order and intelligence has convincingly documented that performances on psychometric intelligence tests decline slightly from firstborns to laterborns. By contrast, the search for birth-order effects on personality has not yet resulted in conclusive findings. We used data from three large national panels from the United States (N = 5,240), Great Britain (N = 4,489), and Germany (N = 10,457) to resolve this open research question. This data base allowed us to identify even very small effects of birth o…
Probing birth-order effects on narrow traits using specification-curve analysis
The idea that birth-order position has a lasting impact on personality has been discussed for the past 100 years. Recent large-scale studies have indicated that birth-order effects on the Big Five personality traits are negligible. In the current study, we examined a variety of more narrow personality traits in a large representative sample ( n = 6,500–10,500 in between-family analyses; n = 900–1,200 in within-family analyses). We used specification-curve analysis to assess evidence for birth-order effects across a range of models implementing defensible yet arbitrary analytical decisions (e.g., whether to control for age effects or to exclude participants on the basis of sibling spacing).…
The development of the rank-order stability of the Big Five across the life span.
Several studies have suggested that the rank-order stability of personality increases until midlife and declines later in old age. However, this inverted U-shaped pattern has not consistently emerged in previous research; in particular, a recent investigation implementing several methodological advances failed to support it. To resolve the matter, we analyzed data from two representative panel studies and investigated how certain methodological decisions affect conclusions regarding the age trajectories of stability. The data came from Australia (N = 15,465; Study 1) and Germany (N = 21,777; Study 2), and each study included four waves of personality assessment. We investigated the life spa…