Grit: Perseverance and passion for long-term goals.

Six studies - N = 1,545 and N = 690 adults; N = 138 Ivy League undergraduates; N = 1,218 and N = 1,308 West Point cadets; N = 175 National Spelling Bee finalists

United States; adults, undergraduates, military cadets and spelling-bee finalists.

Six cross-sectional and prospective studies with no randomisation and no preregistration, built on a 12-item self-report scale the authors created for this paper. Outcomes are a mix of self-reported educational attainment, registrar GPA, West Point retention records and the round reached at the Spelling Bee. Graded D as correlational work with a researcher-developed measure - the grade is about design, not about influence, and this paper's influence is enormous.

Grit accounted for an average of 4% of the variance in success outcomes. The number the subsequent literature turned on is in Study 2 - grit correlates with conscientiousness at r = .77, both self-reported. Grit correlates with cognitive ability at r = .02 (not significant) and with self-control at r = .63. Cadets one SD above the mean on grit were more than 60% more likely to complete summer training (beta = .48, OR = 1.62) while the Whole Candidate Score did not predict retention. For cadet GPA, grit r = .06 against self-control r = .13.

High. Every association is observational, and the twin evidence (Rimfeld et al. 2016) shows 88% of the grit-attainment correlation is genetically mediated.

The point estimates survive meta-analysis. The construct claim does not - grit is not distinguishable from conscientiousness (rho = .84 meta-analytically, genetic correlation .86 in twins, 95% shared variance in confirmatory factor analysis) and its incremental validity over conscientiousness is between .000 and .004.