## Sunday, June 23, 2013

### Are models that assume linear utility useful?

I just saw a paper on how the desire of households to match with particular houses could explain housing market dynamics--in particular why house prices are more volatile than incomes.

Performing such an exercise is very difficult, and requires simplifying assumptions.  One of the most important simplifying assumptions in the paper is that utility is linear--that people value their last unit of consumption just as much as their first.  This assumption is clearly wrong--we know that marginal utility diminishes in consumption.  Yet the assumption was necessary to make the model tractable.

So do we know more about the world because of the model or not?  I really don't know.