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By the end of this section, you will be able to:

  • Identify factors that affect demand
  • Graph demand curves and demand shifts
  • Identify factors that affect supply
  • Graph supply curves and supply shifts

The previous module explored how price    affects the quantity demanded and the quantity supplied. The result was the demand curve and the supply curve. Price, however, is not the only thing that influences demand. Nor is it the only thing that influences supply. For example, how is demand for vegetarian food affected if, say, health concerns cause more consumers to avoid eating meat? Or how is the supply of diamonds affected if diamond producers discover several new diamond mines? What are the major factors, in addition to the price, that influence demand or supply?

Visit this website to read a brief note on how marketing strategies can influence supply and demand of products.

What factors affect demand?

We defined demand as the amount of some product a consumer is willing and able to purchase at each price. That suggests at least two factors in addition to price that affect demand. Willingness to purchase suggests a desire, based on what economists call tastes and preferences. If you neither need nor want something, you will not buy it. Ability to purchase suggests that income is important. Professors are usually able to afford better housing and transportation than students, because they have more income. Prices of related goods can affect demand also. If you need a new car, the price of a Honda may affect your demand for a Ford. Finally, the size or composition of the population can affect demand. The more children a family has, the greater their demand for clothing. The more driving-age children a family has, the greater their demand for car insurance, and the less for diapers and baby formula.

These factors matter both for demand by an individual and demand by the market as a whole. Exactly how do these various factors affect demand, and how do we show the effects graphically? To answer those questions, we need the ceteris paribus assumption.

The Ceteris Paribus Assumption

A demand curve    or a supply curve    is a relationship between two, and only two, variables: quantity on the horizontal axis and price on the vertical axis. The assumption behind a demand curve or a supply curve is that no relevant economic factors, other than the product’s price, are changing. Economists call this assumption ceteris paribus    , a Latin phrase meaning “other things being equal.” Any given demand or supply curve is based on the ceteris paribus assumption that all else is held equal. A demand curve or a supply curve is a relationship between two, and only two, variables when all other variables are kept constant. If all else is not held equal, then the laws of supply and demand will not necessarily hold, as the following Clear It Up feature shows.

When does ceteris paribus Apply?

Ceteris paribus is typically applied when we look at how changes in price affect demand or supply, but ceteris paribus can be applied more generally. In the real world, demand and supply depend on more factors than just price. For example, a consumer’s demand depends on income and a producer’s supply depends on the cost of producing the product. How can we analyze the effect on demand or supply if multiple factors are changing at the same time—say price rises and income falls? The answer is that we examine the changes one at a time, assuming the other factors are held constant.

For example, we can say that an increase in the price reduces the amount consumers will buy (assuming income, and anything else that affects demand, is unchanged). Additionally, a decrease in income reduces the amount consumers can afford to buy (assuming price, and anything else that affects demand, is unchanged). This is what the ceteris paribus assumption really means. In this particular case, after we analyze each factor separately, we can combine the results. The amount consumers buy falls for two reasons: first because of the higher price and second because of the lower income.

Questions & Answers

what is market mechanism
thammy Reply
how do you find the marginal line given the input and output?
Greatson Reply
population density
Thompson Reply
what is monopoly
Thompson
what is elasticity of demand?
tunde Reply
Elasticity is a central concept in economic , and is applied in many situations. Elasticity can provide important information about the strength or weakness of such relationship. Elasticity refers to the responsiveness of one economic variable such as quantity demanded, to change in another variable
Lena
such as price. #Price elasticity of demand:which measure the responsiveness of the quantity demanded to a change in price. #cross elasticity of demand:which measure the responsiveness of quantity demanded of one good to a change in the price of another good.
Lena
what are variables
Lekan Reply
marginal cost
Seyi Reply
division of labour
Abdulmumeen Reply
explain Qd=601/3p
mahmud Reply
what is unemployment
Ernest Reply
what is the formula for average revenues
EMMANUEL Reply
please 7 implications of Lionel Robbins definition of economics
Amaka Reply
Problem of economics to the society
Gmzaeeyan Reply
Within 1 or 2 percentage points, what has the U.S. inflation rate been during the last 20 years? Draw a graph to show the data.
Daphne Reply
law of demand is explaining why the demand curve is downward sloping
Tan Reply
the graph would be x axis is quantity and y axis is price, as the price is expensive, there would be less demand therefore less quantity anf vice versa, thats why demand curve is downward sloping
Tan
and*
Tan
problems of economic to the society
onalaja Reply

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Source:  OpenStax, Principles of economics. OpenStax CNX. Sep 19, 2014 Download for free at http://legacy.cnx.org/content/col11613/1.11
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