The problem is if I look at a population that has an IQ between 115 and 120 and scores 20-25% on conscientious I'll find that grit is far more predictive than I

The problem is if I look at a population that has an IQ between 115 and 120 and scores 20-25% on conscientious I'll find that grit is far more predictive than IQ or conscientiousness. But this doesn't tell me anything about how important it is in the general population m But you'd get far different results in the general population.