2  BIS Review 150/2008  blow some steam off the monetary policy, thereby tending to depreciate the exchange rate. This is precisely what the Board of the Central Bank of Chile decided to do in the face of the severe appreciation early this year, by holding the interest rate constant, while in the most likely scenario, had the appreciation not occurred, rates would have increased. There is abundant evidence that pass-through from the exchange rate to inflation is fairly small. Monetary regimes pegging the exchange rate were based on the notion that exchange rate fluctuations were transmitted to inflation on a one-to-one basis. This was the logic, for example, of pegging the exchange rate in Chile in 1979. However, the empirical evidence shows a relatively low pass-through, particularly under floating regimes where the persistence of exchange rate movements is low. Still, despite the low pass-through, the inflationary effects of very acute depreciations such as those recently experienced by most emerging economies, would not be negligible. The final impact of the exchange rate depreciation on inflation will also depend on the behavior of international prices, which have been losing strength in the face of low growth prospects around the world. With respect to monetary aggregates, some efforts have been made to bring them back to monetary policy, but as I said before, not with the intention of setting money targets, but rather because they are useful indicators of future inflationary pressures.
However, as I will discuss below, in practice the rationale for considering monetary aggregates is a little different. What variables should a central bank consider when setting the interest rate? In the regime I just described, the answer to this question is pretty simple: anything affecting inflation over a two-year horizon. Variables such as inflation expectations, wages, output, the exchange rate, commodity prices, and so on, have important effects on inflationary forecasts and must be taken into account when deciding the future path of monetary policy. There are other variables that have caught particular attention and I would like to take a brief look at them. These are the prices of assets (e.g., stocks, housing), the exchange rate and monetary aggregates. Two questions arise with regard to asset prices. One is, should they influence monetary policy decisions? And the other is, what must be done when those prices contain speculative bubbles? I will address this second question in the next section. But it must be noted that we must avoid the confusion between inflation and financial stability. Concern about asset price bubbles and distortions is at the core of financial stability analysis, but its impact on inflation is different. If stock or housing prices affect future inflation, they should be taken into account in monetary policy decisions. And this actually occurs via the effect of these prices on aggregate demand, output and, in the end, inflation. Hence, the monetary policy seems to have a stabilizing effect by leaning against the wind.