Friday, April 22, 2016

The Problem with Macro in one blogpost


Apparently, Nick Rowe slipped up and wrote something about Macro in plain English. David Andalfatto was understandably quite upset and tried to fix things by adding "a bit of formalism".

Then away he goes:


There is a representative agent (this is not necessary, but makes things easy) with additively-separable log preferences defined over consumption sequences {c(t), t = 0,1,...,∞}, with discount factor β. Let R(t) denote the gross real rate of interest (risk-free) earned on a bond held from date t to date t+1. Assume that all individuals can borrow/lend freely at the risk-free rate.

and then this:

Let me consider an endowment economy where each individual is endowed with a deterministic sequence {y(t), t = 0,1,...,∞}.


OK, everybody got that. Representative agent? check. Perfect capital markets? check, lifetime income fixed and known with certainty? check. Time-separable preferences? check.

AAARRRRGGGGHHHHH!!

People, it would be one thing if models like this fit the data, but they don't.

The consumption CAPM is not an accurate predictor of asset prices, The degree of risk aversion required to make the numbers work in the equity premium puzzle is something on the order of 25 or above, the literature is littered with papers rejecting PIH.

So we are being harangued by a model that is unrealistic in the theory and inaccurate to the extreme in its predictions.

And that's pretty much modern macro in a freakin' nutshell.

Mamba out.

Monday, April 18, 2016

Headline Meme: Florida Memorial Edition


People, eating Floridians is tough work. Just ask the tiger referred to in this classic headline:


Tiger recovering after killing Florida zoo worker