But the implications of this had, to date, "not been well-presented to government, nor have issues of measurement error and the implications these have for performance tables".

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Much of the placebo effect seen in clinical trials is the combination of the natural tendency of patients to get better and measurement error.

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The advantage of these moving averages is that they smooth out both seasonal fluctuations and simple measurement error.

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The trouble is that the longer the puzzle continues, the more potentially worrying it becomes, because it becomes less and less likely that simple measurement error explains it.

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But the strategy worked, because United States agencies were allowed to proceed by trial and error, continually adjusting their policies over time in response not to ideology but to hard measurement of the results against societal goals.

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