measured a stand-in

An institution, such as a regulator, certifier, funder, or optimizer, steers by a number that is easier to measure than the real outcome, and the two drift apart. Correct behavior goes uncredited and wrong behavior passes the test. Sometimes people learn to game the number. One example: workplace noise rules rate earplugs by laboratory tests, while the sound reaching workers' ears is never measured, so millions of workers counted as protected keep losing their hearing. The problem persists because the official scoreboard says all is well.