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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 macro economic s
Addo Reply
macroeconomics is the study of economic as a whole level.
Gafar
meaning of positive science
Sumit Reply
positive science it is focused on facts and cause and effect and behavioural relationship and include developmental testing in economic theoreis.
Gafar
what is inflation
Sama Reply
inflation is the general price increase of goods and services in an economy.
tesfie
Inflation is the persistent rise in the general price level
T-Max
inflation is characterized by increase in the general price of goods and services. when there is too much money in circulation. increase in demand of goods pursuing fewer goods. when purchasing power of money decreases .
Ejikeme
inflation is the persistent rise general price level
Habeeb
inflation is the persistent increase in price
Machall
hi
Rafiu
yes
boston
hi
Ayaan
how are you
Ayaan
increase in the general level of price...
sade
what is deflation
Sele
is the gradual decrease of currency exchange in a country.
Gafar
different between demand and quantity demand
Farhan Reply
No difference
MansoorAfghan
demand is the overall demand for it
MansoorAfghan
actually theres no difference
MansoorAfghan
quantity demanded is used in Equilibrium of d and s
MansoorAfghan
for evrything else u use deman
MansoorAfghan
the difference of it is that when demand simply denotes the willingness and a person's ability to purchase. And as against quantity demand represent the amount of an economic good or services desire by a consumer at a fixed price .☺
Gafar
how to calculate inflation
Richard Reply
Explain the factors that have led to high quantity demanded
Ogwang Reply
price of the product increase of price substitute product as people shift to cheap one
Black
what are the methods used by trade union to increase wages of their members?
Black Reply
strike
Pearl
the size of the commodity
Mensah
increase demand of labour decrease supply of labour
Black
I do support your answer Jackel.
keshav
but how do they do it?
Black
by increasing more labour and reduced the suppliers
Mensah
they can not increase labour, they increase demand of labour.
Black
how do they increase demand for labor?
Black
by analyzing the market equilibrium , cost reduction and cost control , savings in time .
yash
decreasing supply of labour are achieved through training and certification that require for you to employed, you must have certificate, also trade union encouraged government to restrict migration into the country causing shortage of labour supply. Note that the aim of union is to enhance life
Black
objective of union: better working conditions, liveable wage, protect member from unfair treatment which are done through negotiations betweens representative and management. known as collective bargaining.
Black
what is the nature of economics?
Tyscar Reply
economics is a social science since it seeks to solve social problem of scarcity
Jamal
main concerns is the decision individuals make on the allocation of scarce resources among the competing wants
Black
in the short run firm produce a positive as long as the price is larger than what?
yoel Reply
what is economic
Bah Reply
economics is the study of managing the resources in order to maximize the needs and satisfy the wants to a great extent in a regulated set-up..
Muhammad
One explanation for deviation when there is no impact on balance of trade
Shaneel
economic s is a social science that deals with human behavior as a relationship between ends and scarce means which has alternative uses
Derokiz
economic is a study of mankind in ordinary business of life
FIDELIS
economics it is the study of social science that deals with human behaviour as relationship between ends and scarce means which have alternative uses
salam
Economic is the use of scarce recourses to attain economic dough effectively and efficiently.
Addo
economics is the study of how humans make decisions in the face of scarcity. Eg. family decision, individual decision, and societal decision.
Gafar
what is diminishing returns
Blessed Reply
what is the difference between calculus linear equation and derivative?
Bti
whats inferior goods?
jaamac Reply
Good having low quality , also known as giffin goods. When income increases people shift to better quality goods . Hence having a negative effect on inferior goods rather than positive relation ( ie when income increases demand increases but not in case of inferior goods ) example wheat and bajra .
yash
What do u understand by the word ENDS in professor Lord L C Robinson definition of Economics?
Kaba Reply
I understand that ENDS is the unlimited needs of human. But we have limited resources to achieve our unlimited needs/wants. Thank you.
Midhun
variable is a factor that can change
nyodb Reply
did you understand definition of variablE
nyodb
what is monopoly
Shahid Reply
A market situation where there is a single seller of a product for the buyers.
harmony
monopoly is when you have a product in the market and only one supplier got this product so he starts rising price and dominate the market, cause this product doesn't have a competitor
Anas
A market structure characterized by a single seller, selling a unique product in the market. In a monopoly market, the seller faces no competition, as he is the sole seller of goods with no close substitute.
Jale
This is a kind of market that only one seller dominate the market without no competition of a y product or seller.
Ojo
what is production possibility curve?
Lisa
a production possibility curve is a diagram that shows two goods produced in an economy in such a way that increase in the production of one good cannot be done without the decrease on the production of the other. there are efficient points, inefficient points and unattainable points on the PPC
The
production possibility curve or frontier is useful analytical tool for illustrating the concepts of scarcity, choice and opportunity costs.
wilflay
The International Year of Soils, 2015 (IYS 2015) was declared by the Sixty-eighth session of the United Nations General Assembly on December 20th, 2013 after recognizing December 5th as World Soil Day.The purpose of the IYS is to raise awarenessworldwide of the importance of soils for food security,
what
what is indifference curve
Evet
Monopoly is the explicit right given to business or entrepreneurship by the government to operate as the only entity in the economy
wilflay
what is economic system ?
wilflay
economical matter solve this system is know as economic system
what
indifference curve is a diagram that shows the combination of only 2 commodities in such a way that each point on the indifference curve gives the same level of satisfaction
The
all consumer is equal consumtion as definite all ..that type curve is indifference curve
what
what is variable?
Rajeev
economic structure of any area is ,city or country is called economic system
Jairam
what is the difference between rational and irrational choice
Amina
help
Amina
Rational choice theory is an economic principle that assumes that individuals always make prudent and logical decisions that provide them with the highest amount of personal utility. ... Most mainstream academic assumptions and theories are based on rational choice theory.
Anas
Irrationality is cognition, thinking, talking, or acting without inclusion of rationality. It is more specifically described as an action or opinion given through inadequate use of reason, or through emotional distress or cognitive deficiency.
Anas
help
Mensah
The meaning of inverse
Mensah
?
Anas
inverse what ? inverse means opposite .. like if ones going down other goes up so inverse relationship
MansoorAfghan
Definition of Inversely Related: Two variables are inversely related when an increase in one variable causes a reduction in the other variable. For example, when the price of a good increases, its quantity demanded decreases.
Anas
what is opotunity cost
salam
is an alternative forgone after the best choice have been selected.for example when you have cocacola and pepsi and you choose cocacola oportunity cost will be pepsi
Amin
explain the meaning of price cealing and price floor..?
Amin
Opportunity cost is the cost express in terms of forgone, alternatives after a choice have been made.
cyril
A price ceiling is the maximum price a seller can legally charge a buyer for a good or service. Consumers must not pay a price above the pries ceiling
Ntui
A price floor is that is imposed to protect consumers it can not be above the equilibrium price. It's the lowest price that producers must accept from a sales
Ntui
A price ceiling is a price control mechanism issued by the government to protect the consumers from high-priced commodities. It goes to set the highest amount a seller can charge per unit quantity of his product. N.B: This price mechanism isn't binding if equilibrium exists.
harmony
A price floor is a price control mechanism that seeks to protect the sellers by setting the lowest amount a seller can receive for his products. In this case, a seller will not sell his products for any amount less than the price floor amount.
harmony

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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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