Within-person grade variability was largely unstable across subjects & ages & not associated with any of 15 variables that typically explain between-person differences in school performance (e.g. IQ, socioeconomic status, personality traits)

Wright, Megan, and Sophie von Stumm. 2020. “Within-person Variability in School Performance.” PsyArXiv. November 6. doi:10.31234/osf.io/5ne37

Abstract: Although thought to be substantial, within-person variability in school grades has not been systematically studied. Here we analysed data from the Twins Early Development Study (TEDS; Nmax = 11,132) to describe within-person variability across grades in English, maths, and science from age 7 to 16 years. We found that within-person grade variability was largely unstable across subjects and ages. Within-person grade variability at age 16 was not associated with any of 15 variables that typically explain between-person differences in school performance (e.g. IQ, socioeconomic status, and personality traits). Also, within-person grade variability did not predict later educational outcomes at ages 18 and 21. Our findings suggest that within-person grade variability is an observable, but not meaningful psychological construct. We conclude that understanding the causes and consequences of within-person grade variability is of limited epistemological value.