# Elasticity consumer theory and demand

The degree to which demand or supply reacts to a change in price is called elasticity. Elasticity varies from product to product because some products may be more essential to the consumer than others. Demand for products that are considered necessities is less sensitive to price changes because consumers will still continue buying these products despite price increases. There are two reasons for this emphasis. Preferences are a natural psychological concept. Faced with choice alternatives, it is reasonable to expect that a consumer will be able to rank the alternatives. But when economists evaluate markets, they would like to have a representation of demand.

If preferences are represented by a utility function, then demand can be derived from maximization of utility for various prices and income.

In this section, we assume that the consumer has preferences that are represented by a utility function, and we then carry out this derivation of demand. Once demand is represented by a function, it can be used to develop a model of exchange, and it can be combined with the supply functions of firms to model trade in a market. Utility functions There are several classes of utility functions that are frequently used to generate demand functions.

Each of these utility functions has specific properties and uses which are discussed below after the demand function for each is derived. Diminishing Marginal Rate of Substitution Each of the utility functions examined below exhibits a property called "diminishing marginal rate of substitution.

Figure 10 below demonstrates this idea. The curve in the figure shows a many combinations of commodities X and Y that all result in the same utility. Combinations of X Elasticity consumer theory and demand Y that produce the same utility level are called an "indifference curve.

The marginal rate of substitution MRS going from x1, y1 to x2, y2 is 3, since the consumer is willing to give up 3 units of Y to get one additional unit of X.

## EconPort - Handbook - Consumer theory - Demand

The MRS going from x2, y2 to x3, y3 is only 1. This reduction in the marginal rate of substitution is one of the main assumptions about preferences or utility beyond the regularity assumptions that were described in earlier sections.

Diminishing MRS is both an intuitive condition on preferences, and also a mild assumption, but in almost all cases it is enough to guarantee that the demand for a commodity decreases as its price increases.

The optimal consumption level for each commodity is determined by setting the slope of the indifference curve through a point x, y equal to the slope of the budget line. Non-optimal consumption point a and optimal point b.

The top graph in figure 12 shows three example budget lines and the tangency, with the optimal consumption point for each. Since the price of X for each of the budget lines is different, and the optimal consumption level for X is different in each of the three cases, the relationship between px, the price of X, and the consumption level of X can be traced out.

The lower graph in figure 12 traces out this relationship for a consumer with the indifference curves shown in the top portion of figure Optimal consumption points for three different prices top and corresponding demand function bottom.

There is an important feature of the Cobb-Douglas utility function that is apparent in this figure. This means that commodities X and Y are neither substitutes for one another nor complements to one another.

## Consumer Choice, Utility Theory, & Elasticity

The analysis below shows how this is done for the Cobb-Douglas utility function. The simplest way to find the slope of the indifference curve is to use implicit differentiation. This tangency condition can be substituted into the budget equation to eliminate either x or y so that the demand for one of the commodities can be obtained.

CES Utility The Constant Elasticity of Substitution CES utility function is useful because this class of utility functions can be used to model commodities that are either substitutes for one another, or complements of one another.

Derived demand for CES utility The technique for determining demand functions is similar to the technique that was used above to determine the demand for the Cobb-Douglas utility function.

The first step is to determine the slope of the indifference curve through a given point x, yand then set the slope of the indifference curve through x, y equal to the slope of the budget equation.In economics, the cross elasticity of demand or cross-price elasticity of demand measures the responsiveness of the quantity demanded for a good to a change in the price of another good, ceteris alphabetnyc.com is measured as the percentage change in quantity demanded for the first good that occurs in response to a percentage change in price of the second good.

## What is 'Demand Theory'

and your economics team calculates price elasticity of demand less than one. just how important and useful the theory of consumer behavior and consumer choice can be.

Price elasticity of demand - PED - is a key concept and indicates the relationship between price and quantity demanded by consumers in a given time period. Apr 21,  · a core topic in Economic Analysis and Atlas Topic description. Elasticity captures how much the quantity demanded or supplied changes when price changes.

The topic covers determinants of elasticity such as availability of substitutes, time horizon, classification of goods, nature of goods (is it a necessity or a luxury?), and the size of the purchase relative to the consumer’s budget. Consumer surplus and price elasticity of demand.

How is consumer surplus affected by the elasticity of a demand curve? When the demand for a good or service is perfectly elastic, consumer surplus is zero because the price that people pay matches exactly what they are willing to pay.; In contrast, when demand is perfectly inelastic, consumer surplus is infinite.

Consumer demand is the willingness and ability of consumers to purchase a quantity of products in a given period of time, or at a given point in time.

Theory of Demand - alphabetnyc.com