In economics, the final using up of goods and services. The term excludes the use of intermediate products in the production of other goods (e.g., the purchase of buildings and machinery by a business). Economists use statistical information on income and purchases to trace trends in consumption, seeking to map consumer demand for goods and services. In classical economics, consumers are assumed to be rational and to allocate expenditures in such a way as to maximize total satisfaction from all purchases. Incomes and prices are seen as consumption's two major determinants. Critics of the model point out that there are many exceptions to rational consumer behaviourfor example, the phenomenon of conspicuous consumption, in which the high price of a product increases its prestige and adds to demand.