Wise words from John Quiggin

Suppose you wanted to establish whether children’s height increased with age, but you couldn’t measure height directly.

One way to respond to this problem
would be to interview groups of children in different classes at
school, and asked them the question Don suggests “On a scale of 1 to
10, how tall are you?”. My guess is that the data would look pretty
much like reported data on the relationship between happiness and
income.

That is, within the groups, you’d find that kids who
were old relative to their classmates tended to be report higher
numbers than those who were young relative to their classmates (for the
obvious reason that, on average, the older ones would in fact be taller
than their classmates).

But, for all groups, I suspect you’d
find that the median response was something like 7. Even though average
age is higher for higher classes, average reported height would not
change (or not change much).

So you’d reach the conclusion
that height was a subjective construct depending on relative, rather
than absolute, age. If you wanted, you could establish some sort of
metaphorical link between being old relative to your classmates and
being “looked up to”.

But in reality, height does increase
with (absolute) age and the problem is with the scaling of the
question. A question of this kind can only give relative answers.

Here is the link.

Addendum: Here is Will Wilkinson on same.