My poorly informed impression is that the key challenge of any data driven investigation is striking the balance between how hard something is to measure and ho

My poorly informed impression is that the key challenge of any data driven investigation is striking the balance between how hard something is to measure and how close it is to what you really want to know. The marshmallow test was so appealing because it was incredibly easy to perform and seemed like it was pretty close to a measure of the kind of self-control and discipline that's needed to succeed in a variety of life's most important challenges.