Introduction -- Teaching to the test: Goodhart's Law and the paradox of metrics -- The ins and outs: the logic model and program evaluation -- The long and short of it: intertemporal problems and undervaluing time -- The problem of per: denominator errors -- The forest and the trees: simplifying complex systems -- Apples and oranges: ignoring differing qualities -- Not everything that can be counted counts: the lamppost problem -- Not everything that counts can be counted: measuring what matters -- The measure of metrics -- Gateways not yardsticks.