Such measurements are not always self-evident. Zipping through city traffic is hazardous so maybe minimising police response time is not an unalloyed good thing. People form their impressions of government competence subjectively, so such rational performance measures have limited political worth. They are fashionable, however. Margaret Thatcher's 1982 financial management initiative set the ball rolling, and Labour has kicked it hard.
Labour is mighty fond of targets.
To its manifesto commitments have been added ad hoc promises, including the prime minister's gargantuan commitment to abolish child poverty. The inverted commas are necessary because the public at large remains in blissful ignorance of much of this, preferring to rely on excited media reports and the evidence of its own eyes and ears as it contemplates local libraries or applies for parking permits. The Treasury's PSAs were meant to drive the amounts of money departments were given in the 2000 spending review, but Labour's panic over health put paid to that - Tony Blair announced a huge increase for the NHS regardless of performance measures. Critics do not like the PSAs' false precision. Specifying the state's outputs is tricky.