"Any observed statistical regularity will tend to collapse once pressure is placed upon it for control purposes." (Goodhart 1975) Or: "When a measure becomes

"Any observed statistical regularity will tend to collapse once pressure is placed upon it for control purposes." (Goodhart 1975) Or: "When a measure becomes a target, it ceases to be a good measure." (Strathern 1997) Source: https://en.wikipedia.org/wiki/Goodhart%27s_law https://en.wikipedia.org/wiki/Goodhart%27s_law Graham invents the notion of "authoritarian" tests, like school exams, and non-authoritarian tests, like football matches. But this is a poor distinction. Originally, sports were a genuine test of physical prowess. Eventually, the institution took over by enforcing rules. This is the same situation in education, except mental prowess is considered.