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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

using the graph illustrate all the types of elascity
Umar Reply
ha
Nathaniel
.
Anjali
distinguish between increase in demand curve and extenaion in demamd curve
Farhan Reply
what are the shapes of an indifference curve?
Ovensi Reply
division of labour is simply the breaking of job functions so that each individual is engage to one set or the other for easy delivery
EMMANUEL Reply
What is division of labor
peter Reply
it is also simply the breaking down of work into various part so that each individual is entitle to one for easy delivery
EMMANUEL
it is the simplifying of tasks into smaller easily workable divisions where each person specialises on what they understand better
cabs
ok
EMMANUEL
thanks for your briefing and time
EMMANUEL
what are the sources of monopoly power?
Winnerman Reply
the first source, are informations
amine
political power and influence in monetary institutions
Shahul
what is imperfect competition ?
SHAH Reply
the situation in which elements of monopoly ( R&D, EOS and stability of prices etc.) allow individual producers or consumers to exercise some control over market prices
Ghulam
how to find shut down
Sowmya Reply
where p is less than avc
Koushik
s
Shahul
which is the best public finance economics text book?
Shahul
hello
shafiullah
hello
Shahul
Yes hi
Pov
....
SHAH
what are the alternatives various of economic system
olaleye Reply
what is microeconomics
Ayedun
Micro-economics refers to the branch of economics which deals with smaller unit or element of the economy.
Amadu
or Is the study of individual economic unit in a economy..
Neriel
micro economis is the studay of how Households and firms make decision and they interecr it.
mahad
what is financial intermediaries?
Imran Reply
financial intermediaries are those who are link between borrowers and lenders for.eg bank... Bank is a financial intermediary
Ajit
tnx a lot of u
Imran
most welcome
Ajit
why do you here ? why do you want to learn economics
Ajit
والله العظيم انا ماعاوز اتعلمها
انا باخدها غصب عني في الكليه حضرتك
لس كدااا
I am student of ecnomics ,
Imran
Imran
Abdi
yes Abdi temam
Imran
am good too see you
Abdi
tnx why not
Imran
b/c im student
Abdi
great, now I am sleeping see u nex time ok
Imran
ok
Abdi
OK
Ajit
what is the law of dimis
Toyin Reply
what is the feature of public ownership of production factors
Toyin
what is the demand for commodity that posses identical utilities called
Toyin
law of diminishing utility...as the quantity consumed of a commodity increases,the utility derived from each successive unit goes on decreasing... condition___ consumption of other commodities remaining the same.
Malik
sorry it's...Law of diminishing marginal utility
Malik
demand for commodities that posses identical utilities? The commodities having identical utilities are perfect substitutes...and the demand for such type of commodities is called "Competitive Demand".
Malik
thanks
Toyin
Why many people can't differentiate Economists and financial analysts
Hatimu
what is the function of the central bank in an economic?
Toyin
the central bank may lend some money to banks if necessary
konglan
what economics
Toyin Reply
Is this a question?
Tala
is the study of how societies allocate and manage their scare resources
Neriel
What is populatiin
Azer Reply
Population is a number of people living in a particular area within a particular time
Rabby
Population is the number of people living in a particular geographical area within a particular time
Rabby
how does this chat work
Dalaya
ya the ideas are good thanks friends
South
so what's the next question?
South
what is demand schedule
Toyin Reply
is a tabular representation of the quantity demanded of a particular product at a particular price over a given period of time
Loveth
thanks
Toyin
you are welcome
Loveth
ok
Hassan
What is Monetary Mass
Acha 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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