Economists are starting to broaden the idea of cost, in particular talking about the cost of happiness. Quantitative hedonics, then, is an attempt to measure misery or its inverse, joy. The basic idea is easy enough: if you rate your happiness sitting in the garden this morning at 6/10 without an ice cream and 7/10 with one, and an ice cream costs £1, then it costs £1 to increase your happiness 10%.
Nick Cohen in today's Observer discusses an example of this: the cost of aircraft noise. Clearly being overflown makes people miserable. How much should the airlines pay to compensate the people they inflict this on? Obviously one cannot get an unequivocal answer, but even an estimate is interesting.
This view of the world suggests a different way at looking at some problematic modern situations. For instance recently the New York Times had a discussion of babies on public transport. One side took the view that a screaming child make the whole experience miserable for everyone: the other that they had a perfect right to travel with their child no matter how noisy. It would be interesting of debating whether it is acceptable to travel with a screaming infant what the hedonic cost of doing so was. Perhaps if this added onto the parent's ticket their decision to travel might be different?