Other wrinkles complicate response-time measurement, such as human error.

WSJ: All Heat, No Light, in Fire Data

Sunderland tried to muster a response but struggled retain possession before Fulop's error from Ngog's hooked cross allowed a grateful Benayoun to slot home.

BBC: Liverpool 2-0 Sunderland

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.

NEWYORKER: Testing, Testing

The AmVets service organization is "encouraged" by the VA's response to the situation, and pleased to see they caught the error, said spokesman Ryan Gallucci.

CNN: VA to apologize for mistaken Lou Gehrig's disease notices

Of course, the financial crisis explains this massive forecasting error, but the study finds that relatively little was due to fiscal stimulus programmes in response to the downturn.

BBC: Debt and the crisis: How did governments get it so wrong?