Any kind of performance can be measured—reliably and with considerable precision. We can measure the performance of poets, managers, teachers, and politicians—not just that of production workers and athletes. The belief that the more complex forms of performance are not subject to measurement and quantification arises simply from ignorance about how to do it. Once you get the knack, performance that you once thought unmeasurable will usually be not nearly so difficult to measure as, say the radiation of Martian soil or the fertility of farm land.
—Thomas F. Gilbert1
It is difficult to correlate output, particularly the output of human performance, with value. But it can be done. It starts with knowing the desired outcome, ...