Duckworth et al. (2007). In a study by Duckworth & Quinn (2009) grit was found to be a better predictor of academic success than IQ and, surprisingly, grit was negatively correlated to IQ.
I find the research into grit interesting. It fits with Carol Dweck's research into the growth mindset and Anders Ericsson's research into deliberate practice and elite performance. A long term focus, persistence, and resilience are important prerequisites for building high levels of expertise or competence.
At the same time, the research into grit seems to be still in its infancy. An important question I have about the grit concept is what long term passions or goals precisely look like. If you look at the tool with which Duckworth and her colleagues measure grit (see here), this does not become quite clear. At which level do these long term goals have to be specified. Does it matter whether they are defined in terms of achievements or in terms of learning? How narrow or specific do these goals or passions have to be? To which degree are they static or dynamic? I imagine that, as a young person, you cannot oversee how your life will evolve and that your experiences affect how you will think about what your passion or long term goals are and how they will change or evolve. Is is perhaps so that thinking about your long term goals or passions is a continuous process in which you keep refining and redefining what they are? In what I have now read I have not found answers to these types of questions and I am keen to learn more.