What is the exact nature of the consumption function? Can this term be
defined so that it will be consistent with empirical evidence and a
valid instrument in the hands of future economic researchers and policy
makers? In this volume a distinguished American economist presents a new
theory of the consumption function, tests it against extensive
statistical J material and suggests some of its significant
implications.
Central to the new theory is its sharp distinction between two concepts
of income, measured income, or that which is recorded for a particular
period, and permanent income, a longer-period concept in terms of which
consumers decide how much to spend and how much to save. Milton Friedman
suggests that the total amount spent on consumption is on the average
the same fraction of permanent income, regardless of the size of
permanent income. The magnitude of the fraction depends on variables
such as interest rate, degree of uncertainty relating to occupation,
ratio of wealth to income, family size, and so on.
The hypothesis is shown to be consistent with budget studies and time
series data, and some of its far-reaching implications are explored in
the final chapter.