Delayed Gratification Is A Powerful Predictor Of Future Income

Traditional methods used by psychologists (such as correlations and regression) haven't allowed for a simultaneous comparison of different factors relating to an individual's affluence. This study collected a large amount of data -- from more than 2,500 diverse participants -- and split them into a training set and a test set. The test set was put aside while the training set produced model results. The researchers then went back to the test set to test the accuracy of their findings. 

Unsurprisingly, the models indicated that occupation and education were the best predictors of high income, followed by location (as determined by zip code) and gender -- with males earning more than females. Delay discounting was the next most-important factor, being more predictive than age, race, ethnicity or height.

From here citing:

William H. Hampton, Nima Asadi, and Ingrid R. Olson, "Good Things for Those Who Wait: Predictive Modeling Highlights Importance of Delay Discounting for Income Attainment." Frontiers in Psychology (2018). DOI: 10.3389/fpsyg.2018.01545