This paper presents a theoretical model of consumption behavior that synthesizes the seminal contributions of Keynes (1936), Friedman (1956) and Duesenberry (1948). The model is labeled a “relative permanent income” theory of consumption. The key feature is that the share of permanent income...

One of the most enduring relationships in economics is that proposed by Ernst Engel in 1857: “The poorer is a family, the greater is the proportion of the total outgo [family expenditures] which must be used for food. … The proportion of the outgo used for food, other things being equal is...