Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Evidence is provided on the PPP hypothesis using a sample of 50 Spanish cities for a long time period through the application of panel data unit root tests. Although results suggest non-rejection of the PPP, short-run deviations - as measured by half-lives - indicate that real factors might be causing a slow rate of convergence to a common price index, even in highly integrated economies.