This is just inherent in the forecasting process. One reason is that there are a host of potential factors which cannot be incorporated easily in a numerical forecast. Unexpected changes in exchange rates, bond rates, property prices and share prices, the effects of financial structure changes, and so on can have important effects.
Dear friends and colleagues, We are paying more attention than ever before to the possibility of policy normalizations in the major advanced economies that implemented quantitative easing policies over the past few years, and to the influences that this will have on the international financial markets and emerging market economies. Needless to say, normalization does not necessarily mean a return to the pre-crisis state.