DOIAbstract
The merit of economic models is that they make interdependencies explicit, and measure their effects quantitatively, thereby making it possible to make conditional projections, if not to make true predictions. They also permit retrospective analysis, which can be rich in information. It is always necessary to take account of their limitations. The recent past, the point of departure for their projections, is often not well known. The unavoidable introduction of exogenous data restricts the extent of their explanatory power and renders uncertain the projections they make. The relationships on which they are based do not take into account likely structural changes, which are usually slow but which can be sudden. On the basis of these consid...