Publications

Abstract

Many people have flipped coins but few have stopped to ponder the statistical and physical intricacies of the process. We collected 350,757 coin flips to test the counterintuitive prediction from a physics model of human coin tossing developed by Diaconis, Holmes, and Montgomery (DHM; 2007). The model asserts that when people flip an ordinary coin, it tends to land on the same side it started. Our data support this prediction: the coins landed on the same side more often than not, Pr⁡(same side)=0.508, 95% credible interval (CI) [0.506, 0.509], BFsame‐side bias=2359. Furthermore, the data revealed considerable between-people variation in the degree of this same-side bias. Our data also confirmed the generic prediction that when people flip an ordinary coin—with the initial side-up randomly determined—it is equally likely to land heads or tails:Pr⁡(heads)=0.500, 95% CI [0.498, 0.502], BFheads‐tails bias=0.182. Additional analyses revealed that the within-people same-side bias decreased as more coins were flipped, an effect that is consistent with the possibility that practice makes people flip coins in a less wobbly fashion. Our data therefore provide strong evidence that when some (but not all) people flip a fair coin, it tends to land on the same side it started. Supplementary materials for this article are available online, including a standardized description of the materials available for reproducing the work.

Abstract

Acknowledging that the parent–child attachment is a dyadic relationship, we investigated differences between pairs of parents and preschool children based on gender configurations in the association between attachment and problem behavior. We looked at mother–daughter, mother–son, father–daughter, and father–son dyads, but also compared mothers and fathers, daughters and sons, and same versus different gender pairs. We employed multigroup structural equation modeling to explore moderation effects of gender in a sample of 446 independent pairs of parents and preschool children (2–5 years old) from the Netherlands. A stronger association between both secure and avoidant attachment and internalizing problems was found for father–son dyads compared to father–daughter dyads. A stronger association between both secure and avoidant attachment and externalizing problems was found for mother–son dyads compared to mother–daughter and father–daughter dyads. Sons showed a stronger negative association between secure attachment and externalizing problems, a stronger positive association between avoidant attachment and externalizing problems, and a stronger negative association between secure attachment and internalizing problems compared to daughters. These results provide evidence for gender moderation and demonstrate that a dyadic approach can reveal patterns of associations that would not be recognized if parent and child gender effects were assessed separately.