It is evident from general experience that price of same good
may differ considerably among countries, regions, cities in same country
and even adjacent shopping malls and outlets. It is also common
knowledge that stronger competitive forces and information about market
price tend to ensure convergence of prices. In the presence of these
forces price differentials cannot be persistent and are hence short
lived. The recent literature on price convergence has focused on country
studies using regional commodity prices and Consumer Price Index (CPI)
data.1 The analysis of relative prices or real exchange rates between
regions or cities in a country has certain advantages in estimating
Purchasing Power Parity (PPP) puzzle. There are no trade barriers and
non tradable goods in a single country. Krugman and Obstfeld (2007)
consider transportation costs, trade barriers and goods market
segmentations as obstacles to hold international Ppp.Furthermore they
mention that countries have different endowments, baskets of goods and
consumption weights in their inflation index. So PPP may not hold even
if there are no non tradable goods and barriers. The PPP theory is
related to the law of one price through arbitrage of international
goods. The estimation of real exchange rates among countries shows that
the convergence towards PPP is very slow.2 This study attempts to use
overall Consumer Price Index (CPI) data on 35 Pakistani cities from July
2001 to June 2008 to estimate relative city price convergence with
Karachi and Lahore, two numeraire cities. The case of Pakistan is
interesting primarily due to the following reasons.