Reasons Grit is Alive and Well

• John Vandivier

<a href="http://psycnet.apa.org/index.cfm?fa=search.displayrecord&uid=2016-06824-001">Rimfeld et al (2016), a current and well received paper, gives academic credibility to a rumor I've heard around the GMU campus. The rumor is that the <a href="https://en.wikipedia.org/w/index.php?title=Grit_(personality_trait)&oldid=761415235#Scientific_findings">personality trait called grit which was <a href="http://psycnet.apa.org/journals/psp/92/6/1087/">pioneered by Duckworth has reached a dead end as a research program. The present article disagrees strongly.

Rimfeld et al argue that grit is essentially the same trait as <a href="https://en.wikipedia.org/w/index.php?title=Conscientiousness&oldid=760419198">conscientiousness, and therefore adds nothing to the prior literature which establishes <a href="https://en.wikipedia.org/w/index.php?title=Big_Five_personality_traits&oldid=765739426">Big 5 personality traits as predictive of success.

First, let me admit that the "True Grit" study was largely well done. At the same time, I think the study provides great evidence in the direction opposite its own conclusion:

  1. By its own admission, grit outperforms 4 of the Big 5 personality traits.
    1. In significance, coefficient size, and explanatory power.
  2. By its own admission, grit adds 10% to the explanatory power of the Big 5 model alone.
    1. The Big 5 model explains 6% of the variation, while the addition of grit adds another statistically significant .6% (although it is mentioned as .5% in an interview with Rimfeld.)
    2. Any market firm would consider such a gain to be a huge competitive advantage. Any investor would consider it a solid ROI. Why is 10% not economically important?
    3. Here's a plausible pro-unimportance argument: Government policies to fund a grit training would
  3. The study used low-precision instruments and yet still found important and significant effects.
  4. The study presents clearly weak arguments against the malleability of grit.
    1. Other very fresh literature strongly suggests grit may be more malleable, trainable, or acquired compared to other Big 5 traits.
  5. Grit may suffer a masking effect from aggregation of two or more subfactors. If so,
In addition to the 5 points outlined above, I will state that I find the genetic argumentation in the paper entirely unconvincing. This sort of analysis permeates the related literature, however, and it may reflect my own ignorance rather than the widespread methodological problem it seems in my view. Why do I find the genetic argumentation unconvincing?
  1. The genetic differences are claimed on a differential between paternal and maternal twins, but these twins were not separated at birth. So I do not see how the environmental effects can be cleanly delineated.
  2. The claim that shared environmental factors have no explanatory power supports the intuition behind criticism #1, which is that there is a faulty attribution of shared environmental effects to genetic differences.
  3. The genetic differences themselves are not clean: The analysis shows the difference between paternal and maternal twins. This does not genuinely signal genetic differences: It signals differences attributable to the Y chromosome. The X chromosome obtains no variation.
    1. It follows that if the X chromosome obtains high explanatory power then genetic correlation will be overstated.
    2. This is plausible considering the decomposition of grit into \"cold grit\" and passion, where passion or emotional effects are intuitively linked to gender.
    3. Or, perhaps my gender intuition is wrong. I'm far from a gender expert.
    4. Here's a cherry picked article claiming a link between gender and emotion. Here's an article against gender and passion. I haven't done a real literature review.
Given the above points, and the further content of that study and the broader literature, I find it entirely implausible to claim either of the following:
  1. Grit has an unimportant, insignificant, limited-application, or non-robust effect.
  2. Grit as a research project is a dead end. The important questions around grit have already been answered and it turns out that it is essentially the same thing as conscientiousness.