The Big Mac Index Two Decades On An Evaluation Of Burgernomics

The Big Mac Index, introduced by The Economist magazine more than two decades ago, claims to provide the “true value” of a large number of currencies. This paper assesses the economic value of this index. We show that (i) the index suffers from a substantial bias; (ii) once the bias is allowed for, the index tracks exchange rates reasonably well over the medium to longer term in accordance with relative purchasing power parity theory; (iii) the index is at least as good as the industry standard, the random walk model, in predicting future currency values for all but shortterm horizons; and (iv) future nominal exchange rates are more responsive than prices to currency mispricing. While not perfect, at a cost of less than $US10 per year, the index seems to provide good value for money.