"The value of the measure will evaporate"

"A few years ago I interviewed General H. R. McMaster, an expert on the mistakes made in Vietnam. He told me that the army used to believe that “situational understanding could be delivered on a computer screen.”

It could not. Sometimes you have to be there to understand—especially when a situation is fast-moving or contains soft, hard-to-quantify details, [Moi ici: Mal li isto recordei logo uma pergunta que me fizeram na semana passada durante este webinar, sobre auditorias remotas no sector alimentar] as is typically the case on the battlefield. The Nobel laureate economist Friedrich Hayek had a phrase for the kind of awareness that is hard to capture in metrics and maps: the “knowledge of the particular circumstances of time and place.”

Social scientists have long understood that statistical metrics are at their most pernicious when they are being used to control the world, rather than try to understand it.

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"When a measure becomes a target, it ceases to be a good measure.") Psychologists turn to Donald T. Campbell, who around the same time explained: “The more any quantitative social indicator is used for social decision-making, the more subject it will be to corruption pressures and the more apt it will be to distort and corrupt the social processes it is intended to monitor.”

Goodhart and Campbell were onto the same basic problem: a statistical metric may be a pretty decent proxy for something that really matters, but it is almost always a proxy rather than the real thing. Once you start using that proxy as a target to be improved, or a metric to control others at a distance, it will be distorted, faked, or undermined. The value of the measure will evaporate.”[Moi ici: Ainda perguntam porque é que este é um livro a ler em tempos de maioria absoluta?]

Trechos retirados de "The Data Detective" de Tim Harford