When income increases and the demand for a good increases the good is considered a

Consumer demand and income

Consumer income (Y) is a key determinant of consumer demand (Qd). The relationship between income and demand can be both direct and inverse.

Normal goods

In the case of normal goods, income and demand are directly related, meaning that an increase in income will cause demand to rise and a decrease in income causes demand to fall. For example, for most people, consumer durables, technology products and leisure services are normal goods.

Inferior goods

In the case of inferior goods income and demand are inversely related, which means that an increase in income leads to a decrease in demand and a decrease in income leads to an increase in demand. For example, necessities like bread and rice are often inferior goods.

It should be noted that ‘normal’ and ‘inferior’ are purely relative concepts. Any good or service could be an inferior one under certain circumstances. Even luxury goods can become inferior over time. Video players were once luxuries, but as incomes rose consumers switched to DVDs. Of course, DVD’s have been replaced by digital downloads, on-demand TV, and streaming services like Netflix.

Engel curves

Engel Curves, named after 19th Century German statistician Ernst Engel, illustrate the relationship between consumer demand and household income.

Engel curves for normal goods slope upwards – the flatter the slope the more luxurious the good, and the greater the income elasticity. In contrast, Engel curves for inferior goods have a negative slope.

Demand for the three goods, shown here, all respond very differently to the same change in income, Y to Y1. Demand for the normal good increases from Q to Q1, demand for the luxury good rises much more, to Q2, and demand for the inferior good falls from Q to Q3.

See also:

Indifference curves and normal goods

If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

(shifts in the entire supply​ curve) are the result of changes in variables other than the​ good's own price. Changes in the following variables cause a shift in the entire supply​ curve:

1. Prices of inputs. When input prices increase​ (decrease), the amount of the good or service that firms are willing and able to supply decreases​ (increases) due to a change in the cost of production.

2. Technological change. Technological advances often streamline the production process and increase the amount of the product firms are able to produce at all prices.

3. Prices of substitutes in production. If a firm can produce similar​ goods, it might shift production resources into the good that has the higher market price.

4. Number of firms in the market. If there are more​ (fewer) firms in the​ market, supply increases​ (decreases).

5. Expected future prices. A firm might postpone production of a good or service to wait for higher expected future prices. As a​ result, current supply falls.

What Is the Income Effect?

The income effect, in microeconomics, is the resultant change in demand for a good or service caused by an increase or decrease in a consumer's purchasing power or real income. As one's income grows, the income effect predicts that people will begin to demand more (and vice-versa).

So-called normal goods will exhibit this typical pattern. Inferior goods, on the other hand, may see their demand actually fall as income increases. An example of such an inferior good could be store-brand items: as people become wealthier they may opt instead for more expensive name brands,

Key Takeaways

• The income effect describes how an increase in income can change the quantity of goods that consumers will demand.
• For so-called normal goods, as income rises so does the demand for them (and vice-versa).
• This is reflected in microeconomics via an upward shift in the downward-sloping demand curve.
• This effect, however, can vary depending on the availability of substitutes and the good's elasticity of demand.
• For inferior goods, the income effect dominates the substitution effect and leads consumers to purchase more of a good, and less of substitute goods, when the price rises.

Income Effect

Understanding the Income Effect

The income effect is a part of consumer choice theory—which relates preferences to consumption expenditures and consumer demand curves—that expresses how changes in relative market prices and incomes impact consumption patterns for consumer goods and services. For normal economic goods, when real consumer income rises, consumers will demand a greater quantity of goods for purchase.

The income effect and substitution effect are related economic concepts in consumer choice theory. The income effect expresses the impact of changes in purchasing power on consumption, while the substitution effect describes how a change in relative prices can change the pattern of consumption of related goods that can substitute for one another.

Changes in real income can result from nominal income changes, price changes, or currency fluctuations. When nominal income increases without any change to prices, this means consumers can purchase more goods at the same price, and for most goods, consumers will demand more.

If all prices fall, known as deflation and nominal income remains the same, then consumers’ nominal income can purchase more goods, and they will generally do so. These are both relatively straightforward cases. However in addition, when the relative prices of different goods change, then the purchasing power of consumer’s income relative to each good changes—then the income effect really comes into play. The characteristics of the good impact whether the income effect results in a rise or fall in demand for the good.   

When the price of a product increases relative to other similar products, consumers will tend to demand less of that product and increase their demand for the similar product as a substitute.

Normal Goods vs. Inferior Goods

Normal goods are those whose demand increases as people's incomes and purchasing power rise. A normal good is defined as having an income elasticity of demand coefficient that is positive, but less than one.

For normal goods, the income effect and the substitution effect both work in the same direction; a decrease in the relative price of the good will increase quantity demanded both because the good is now cheaper than substitute goods, and because the lower price means that consumers have a greater total purchasing power and can increase their overall consumption.

Inferior goodsare goods for which demand actually declines as consumers' real incomes rise, or rises as incomes fall. This occurs when a good has more costly substitutes that see an increase in demand as the economy improves. For inferior goods, the income elasticity of demand is negative, and the income and substitution effects work in opposite directions.

An increase in the inferior good’s price means that consumers will want to purchase other substitute goods instead but will also want to consume less of any other substitute normal goods because of their lower real income.

Inferior goods tend to be goods that are viewed as lower quality, but can get the job done for those on a tight budget, for example, generic bologna or coarse, scratchy toilet paper. Consumers prefer a higher quality good, but need a greater income to allow them to pay the premium price.

Example of Income Effect

Consider a consumer who on an average day buys a cheap cheese sandwich to eat for lunch at work, but occasionally splurges on a luxurious hot dog. If the price of a cheese sandwich increases relative to hotdogs, it may make them feel like they cannot afford to splurge on a hotdog as often because the higher price of their everyday cheese sandwich decreases their real income.

In this situation, the income effect dominates the substitution effect, and the price increase raises demand for the cheese sandwich and reduces demand for a substitute normal good, a hotdog, even if the hotdog's price remains the same.

What Does the Income Effect Depict?

The income effect is a part of consumer choice theory—which relates preferences to consumption expenditures and consumer demand curves—that expresses how changes in relative market prices and incomes impact consumption patterns for consumer goods and services. In other words, it is the change in demand for a good or service caused by a change in a consumer's purchasing power resulting from a change in real income. This income change can be the result of a rise in wages etc., or because existing income is freed up by a decrease or increase in the price of a good that money is being spent on.

What Is the Difference Between the Income Effect and the Price Effect?

The difference between the income effect and the price effect is that the income effect evaluates consumer spending habits based on a change in their income. The price effect instead considers consumer spending habits based on a change in the price of a good or service.

What Is Substitution Effect?

The substitution effect is the decrease in sales for a product that can be attributed to consumers switching to cheaper alternatives when its price rises. A product may lose market share for many reasons, but the substitution effect is purely a reflection of frugality. If a brand raises its price, some consumers will select a cheaper alternative.

What Are Normal Goods?

Normal goods are those whose demand increases as people's incomes and purchasing power rise. As such, a normal good will have a positive income elasticity of demand coefficient but it will be less than one. This means that a decrease in the relative price of the good will result in an increase in quantity demanded both because the good is now cheaper than substitute goods, and because the lower price means that consumers have a greater total purchasing power and can increase their overall consumption.

What Are Inferior Goods?

Inferior goods are goods for which demand declines as consumers' real incomes rise, or rises as incomes fall. Consumers with more money may opt to buy more expensive substitutes instead of what they could afford only when incomes were lower.

The Bottom Line

The income effect identifies the change in consumers’ demand for goods and services based on their incomes. In general, as one's income rises, they will begin to demand more goods. Similarly, A decrease in income results in lower demand. The marginal propensity to spend and the marginal propensity to save are looked at when determining the influences of the income effect. The substitution effect also plays a role in how consumers spend their income in times of rising or declining income. For normal goods the income effect works as predicted. For inferior goods, it works in the opposite direction.

When a rise in income increases the demand for a good?

When an increase in income causes demand for a good to rise that good is an inferior good?

When income increases and demand shifts right the good is?