But the measurement of Conscientiousness was much worse, and it still outpredicted Grit considerably: "Given the NLSY 2-item measure of conscientiousness and t

But the measurement of Conscientiousness was much worse, and it still outpredicted Grit considerably: "Given the NLSY 2-item measure of conscientiousness and the 8-item measure of grit, this comparison is likely to overestimate the effect of grit relative to conscientiousness (Crede et al., 2012 for the consequences of using short measures of the Big Five personality traits)." Plus, going from an 8-item test to a longer one isn't going to close a gap with IQ that large, and as they point out, the reliability is decent enough and pro-Grit authors have no trouble making claims based on, so what's sauce for the goose is sauce for the gander: "The reliability of the scale in our data was .72, which is comparable to the reliability reported by Duckworth and Quinn (2009) and within the ranges reported in the meta-analysis of Crede et al. (2017)."