■ Zero costs. When there are no trade costs (c = 0), q = 1, and the law of one price
(LOOP) holds exactly. This is shown in Figure 22-1, panel (a).
■ Low costs. When c is low, the deviations from PPP (and LOOP) will be small.
■ High costs. When c is large, the deviations from PPP (and LOOP) will be large.
The real exchange rate can fluctuate within a larger no-arbitrage band, shown in
Figure 22-1, panel (c).
When the costs of arbitrage are higher, the deviations from PPP and LOOP will be larger.
Trade Costs in Practice Recent research indicates that trade costs are affected by market
conditions, characteristics of goods, and economic policy. We consider these factors in
turn:
■ Transportation costs:
■ Trade policy:
● Average tariffs are 5% for advanced economies, 10% for developing
countries.
■ Other costs may arise from: