George Jonas' latest on the census long-form plumbs the depths of innumeracy:
At least, that’s the mantra. Self-selection skews data. No one explains why coercion doesn’t skew data the other way, or why doesn’t it bother statisticians if it does, or why data can’t be adjusted for self-selection when it can for most other things.
The answer to the last bit, about adjusting for self-selection, is of course that data can be adjusted for self-selection where you have census data to correct it with.
But its the first part that's most interesting. Jonas is suggesting, obliquely, that there is nothing but skew--skew this way, skew that way, the further implication being that these directions are "left" and "right", politically, and that statisticians tend towards socialism.
But of course that's not accurate: to any question about the demographics of an area, there is a correct answer, and you get that answer when you have managed to extract (via the mandatory long-form) a truly random sample from within that area (ie a sample that is unskewed). Underlying Jonas' argument, then, is an appeal to truth relativism.
Which, you would think, is weird coming from a Conservative, but perhaps more common than you might think.