Since the first statement of the aims and methods of the Cambridge
Growth Project, which appeared in 1962 as the first number of our former
series A Programme for Growth, we have produced a volume on the state
ofthe model and on projections derived from it at roughly five year
intervals: Exploring 1970 (1965), Exploring 1972 (1970) and now the
present book. A comparison of these publications shows the directions in
which we have developed our model. First, we have been able to model
more parts of the economy and to model them better; and, second, by
adopting a targets-and-instruments approach, we have been able to tackle
questions of policy. As a consequence of the first of these
improvements, the model has become more closely knit and variables which
were previously exogenous have become endogenous; and, as a consequence
of the second, the model has become less rigid and can be used to
suggest policies for correcting some ofthe undesir- able features that
emerge from the projections.