Gilbert's First Leisurely Theorem
"Human competence is a function of worthy performance (W), which is a function of the ratio of valuable accomplishments (A) to costly behavior (B)" (Gilbert 2007).
Gilbert's First Leisurely Theorem aims to explain the difference between accomplishment and behavior. It tells us that the accomplishment is what makes it valuable, not the behavior, and therefore, we need to try to get great results with as little effort as possible (Gilbert 2007). 
W = A/B

Corollaries of the First Leisurely Theorem
 If we know what we are doing, education must be highly economical. Essentially, this means that if we invest in behavioral costs (i.e. spend effort getting an education), and they can produce great changes in accomplishment, that means that the performance after the cost investment will generally be a worthy performance.
 We have no need to measure behavior until we have measured accomplishment. We have no reason to look at what is causing a decline in accomplishment until we have established that there is, in fact, a decline.
 Quantitative expressions of behavior (B measures), except for special purposes, are often misleading indices of performance. This essentially means that test scores are usually misleading.
(Gilbert 2007)