Conscientiousness vs. working hard

South Korea ranks second to last in terms of conscientiousness but also ranks first in the number of hours worked.  South Korea is not an anomaly.  Country-level reports of Big Five conscientiousness are unrelated to the number of hours worked.  The rank correlation between hours worked and conscientiousness across countries is negative, though statistically insignificant.

That is from “Some Contributions of Economics to the Study of Personality,” a new working paper by James J. Heckman, Tomas Jagelka, and Timothy D. Kautz.  How do you interpret these numbers?  That the notion of conscientiousness is poorly measured?  Or that “susceptibility to manipulation by incentives” is a separate quality, highly valued in a workforce, but not well correlated with “conscientiousness as we know it”?