Making (up) the grade? estimating the genetic and environmental influences of discrepancies between self-reported grades and official GPA scores.

Abstract

Academic achievement has been found to have a pervasive and substantial impact on a wide range of developmental outcomes and has also been implicated in the critical transition from adolescence into early adulthood. Previous research has revealed that self-reported grades tend to diverge from official transcript grade point average (GPA) scores, with students being more likely to report inflated scores. Making use of a sample of monozygotic twin (N=282 pairs), dizygotic twin (N=441 pairs), and full sibling (N=1,757 pairs) pairs from the National Longitudinal Study of Adolescent Health (Add Health; 65% White; 50% male; mean age=16.14), the current study is the first to investigate the role that genetic and environmental factors play in misreporting grade information. A comparison between self-reported GPA (mean score of 2.86) and official transcript GPA scores (mean score of 2.44) revealed that self-reported scores were approximately one-half letter grade greater than official scores. Liability threshold models revealed that additive genetic influences explained between 40 and 63% of the variance in reporting inflated grades and correctly reporting GPA, with the remaining variance explained by the nonshared environment. Conversely, 100% of the variance in reporting deflated grade information was explained by nonshared environmental influences. In an effort to identify specific nonshared environmental influences on reporting accuracy, multivariate models that adequately control for genetic influences were estimated and revealed that siblings with lower transcript GPA scores were significantly less likely to correctly report their GPA and significantly more likely to report inflated GPA scores. Additional analyses revealed that verbal IQ and self-control were not significantly associated with self-reported GPA accuracy after controlling for genetic influences. These findings indicate that previous studies that implicate verbal IQ and self-control as significant predictors of misreporting grade information may have been the result of model misspecification and genetic confounding. The findings from the current study indicate that genetic influences play a crucial role in the accuracy in which grade information is reported, but that nonshared environmental influences also play a significant role in specific circumstances. The theoretical and methodological implications of the results are discussed.