The central question of economic policy is the question of the effectiveness of its various instruments. - Jan Tinbergen

For some queer and deplorable reason most human beings are more impressed by words than by figures, to the great disadvantage of mankind.

The advantages of models are, on one hand, that they force us to present a "complete" theory by which I mean a theory taking into account all relevant phenomena and relations and, on the other hand, the confrontation with observation, that is, reality.

The world is in a process of a great transformation. In a considerable part of it a new economic order, "communism," is being vigorously tried out. Elsewhere an old order is passing as one country after another throws of the yoke of colonialism. The wholesale introduction of Western techniques and ways of life shaking the foundations of numerous beliefs and attitudes, for good and for evil.