"You Had One Job" is a thing people say when they find an example of a very simple thing done very badly. E.g.:
The phrase comes to mind this afternoon as the New York Times reports that the Census Bureau picked this year, of all years, to make a change in the way they measure how many Americans have health insurance, the upshot being that it will be "difficult" to measure the effects of the Affordable Care Act on the number of uninsured individuals:
An internal Census Bureau document said that the new questionnaire included a “total revision to health insurance questions” and, in a test last year, produced lower estimates of the uninsured. Thus, officials said, it will be difficult to say how much of any change is attributable to the Affordable Care Act and how much to the use of a new survey instrument.
In other words, last year's numbers will be apples and this year's numbers will be oranges, which the Census Bureau itself admits is "unfortunate timing." And the Census Bureau is typically "the authoritative source of health insurance data," per the Times, though the question of Obamacare's impact is also being studied via private polling by companies like Gallup.
Also, if you're into this sort of thing, the Times piece's explanation of why it's so hard to get a straight answer to a seemingly simple question like "do you have health insurance?" is pretty interesting, and speaks to the existential difficulty of really being able to know anything at all about anything. Check it out.