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.
GDP: used as a proxy for welfare.
But could using other stats in a Prosperity index then create unintended statistical pressures?
