Personality psychologists have generated a huge number of scales. One activity I do with my students is to mix items from several scales and have students attempt to assign then to scales by title (and whatever they happen to know about the scale). This turns out to be a very difficult task. I guess I kind of believe in personality characteristics, but I have trouble with the way such characteristics are measured. When anyone becomes enthralled with a personality “theory”, I recommend that he or she ignore the label and examine the individual items making up the survey.
Anyway, a recent scale (GRIT) has been reported as a predictor of achievement than IQ. I suppose this surprises some folks. There are better predictors of future academic achievement than IQ. Past achievement is a better predictor. This actually makes a lot of sense. Past achievement is the product of many factors – including aptitude. This is the point. IQ scores are used in educational settings because IQ is a measure of aptitude and not the sole predictor of achievement. IQ is used as a way to estimate potential. Other variables determine how close to one’s potential one actually achieves.
The scales I think make a contribution identify a characteristic that is not obvious in existing achievement. For example, asking questions that attempt to identify how a learner explains the level of achievement (attribution theory) is a good example. Personal perception of causation is just that – personal. A given level of achievement with different interpretations can result in different futures.
Anyway, the items from the GRIT scale ask students if they typically persevere. What we learn is that students with a history of being success (by their description) are likely to continue to be successful. This is certainly an interesting characteristic, but it would seem to me that the value is in determining where GRIT comes from. Students who are successful are a good bet to continue to be successful. Hence, GRIT as an independent variable does not seem to be that interesting. We already have existing achievement as an independent variable. To me, GRIT as a scale score becomes interesting if it changes and this change is predictive of future achievement after accounting for past achievement.