Under the managed float, some nations choose target exchange rates and intervene to support them. Target exchange rates are intended to reflect long-term economic forces that underlie exchange-rate movements. One way for managed floaters to estimate a target exchange rate is to follow statistical indicators that respond to the same economic forces as the exchange-rate trend. Then, when the values of indicators change, the exchange-rate target can be adjusted accordingly. Among these indicators are rates of inflation in different nations, levels of official foreign reserves, and persistent imbalances in international payments accounts. In practice, defining a target exchange rate can be difficult in a market based on volatile economic conditions.