Moreover, when asked to choose, diners prefer the individual pay to the inefficient split-bill method.
Like many studies of this type, perhaps that should read "when asked to chose, college sophomores prefer the individual pay to the split-bill method".
Most diners I know prefer the split-bill, precisely because the value of a meal lies in the conviviality (a companion is someone with whom one shares bread), not in the calories or costs of the food. To claim the split-bill method is inefficient perhaps shows that economists (or at least Chicago economists) are penny-wise and pound-foolish, and certainly implies they aren't the best partners for a dinner party.
In fact, splitting the bill is the most economically efficient method, because it imposes a minimum of deadweight accounting costs -- might they have had more realistic results with a college demographic by studying round-buying among friends, rather than dinner-buying among strangers?
-Dave
