In the previous section we referred to various theories in respect to the main determinant of future exchange rates. However, it is actually an empirical topic to identify the most important factors.
As a result, we can argue that forecasting exchange rates is a difficult task because of so many factors that might be regarded as determinants. In addition, using formulas (similar to the Interest Rate Parity Theorem) will result in only imprecise estimates of future currencies exchange, basically because the data related to inflated to inflation differentials and future spot rates are by themselves only estimates (Lumby S. & Jones C. 1999). 
On the other hand, it remains doubtful weather or not the foreign exchange market is an efficient one-since it seems that not all information but only the historical is incorporated in priced (weak form efficiency).