Regression, weighting and related approaches to estimating a population mean from a sample with nonrandom missing data often rely on the assumption that conditional on covariates, observed samples can be treated as random. Standard methods using this assumption generally will fail to yield consistent estimators when covariates are measured with…

This study examined physiological and coping responses to peer-evaluative challenges in early adolescence as predictors of academic outcomes. The sample included 123 young adolescents (X-bar[subscript age]) = 12.03 years) who participated in the summer before (T1) and the spring after (T2) the transition to middle school. At T1, respiratory sinus…

Questionnaires were completed by 5th-, 8th-, and 11th-grade public schools students in rural and suburban school districts and by undergraduates at two universities in the United States (n = 1,242). They were asked about their orientation to video games--the amount of time they played, their motives for doing so, and the game types they…