Differentiate betweenperfectly elastic and also inelasticUnderstand the difference between elasticity top top a single curve and relative elasticityExplain what variables affect elasticity that supply and also demand
(Credit: college of Victoria Students’ Society)

Textbook or Burger?

In object 4.1 and also 4.2, we looked at elasticity on a solitary demand curve and also examined how responsive customer are to price changes at assorted levels that production. But what about responsiveness throughout firms? across industries? We understand that in particular industries, such together the textbook industry, consumers are much less responsive to change than others. Exactly how is the quantity demanded because that textbooks impacted by an increase in price? If the textbook for a course climbed from $100 to $150, what would certainly you do? many students will buy the book anyway, since it is a forced course material. Publishers are significantly using different strategies to ensure the sector stays inelastic or unresponsive to price change, such as bundling the textbook through mandatory course access codes. To compare this instance with the price of a burger. If theprice that a burgess rises native $8 to $12, you might purchase lunch from a different restaurant or start packing lunch from home. The market for textbooks and also burgers are really different. In thissection, we will check out the relative elasticity of different markets.

You are watching: The key factor that determines whether the supply of a good will be elastic or inelastic is

Perfectly Elastic and also Perfectly Inelastic

To begin the conversation about relative elasticity, it help to very first look in ~ the extremes.

Perfectly Elastic

Imagine a product where if the price increased, also slightly, you wouldn’t buy any it anymore. Sound familiar? That’s because we presented this concept in topic 3, as one of the presumptions of a perfectly competitive market. Among the examples we supplied was identical warm dog stands, next by side, where the only distinction was price. If top quality is the same, the rational consumer will always purchase the hot dog that is a lower price. Indigenous the view of the stand, they understand that if they increase price even slightly, castle will market 0 units. This means that ED=∞.

Using point-slope at any allude in number 4.3a, we can confirm this.

\frac\Delta Q\Delta P\cdot \fracPQ=?

We recognize that \frac\Delta Q\Delta P is same to the station of the slope. In the need curve in figure 4.3a, when theΔP>0 thenΔQ is same to∞. This means that \frac\Delta Q\Delta P =∞.

Figure 4.3a


At the other finish of the spectrum, take into consideration a industry where the for sure can continue to boost prices v no readjust in quantity. If you to be poisoned and had come buy the antidote, would you it is in responsive to price change? probably not. This is an instance of a situationwhere demand is practically perfectly inelastic. If you increase the price, quantity demanded does not change.This means that ED= 0.

We can confirm this by using point-slope in ~ any allude in figure 4.4a.

In the demand curve in figure 4.3a, once theΔP>0 thenΔQ is same to 0. This way that \frac\Delta Q\Delta P = 0.

Figure 4.3b

Relative Elasticity

The principles of perfectly elastic and perfectly inelastic command us into a discussion of family member elasticity. In 4.1 and 4.2, we examined a singledemand curve, and also looked in ~ the numerical worth of elasticity follow me thatdemand curve. However, elasticity can additionally be helpful when comparingdemand curves. Also though each need curve has an inelastic, elastic, and unit elastic section, the to compare of the curvescan show which industries are relatively more responsive to price changes.This is crucial concept to know for as soon as we look at the effects of a plan change.

Figure 4.3c

Figure 4.3c illustrates two curves. One is relatively an ext inelastic and also the various other is relatively more elastic. The best way to recognize which is more elastic or inelastic is to to compare each curve to theextremes. The curve more resemblant of perfect elasticity is relatively more elastic, the curve much more resemblant or perfect inelasticity is relatively more inelastic. Note this is various than saying one iselastic and the other inelastic! to emphasize this point,read the section “Bears and also Elasticity.”

Bears and Elasticity

(Credit: Wapster/ Flickr/ CC by 2.0)

A be afflicted with jumps the end of a bush and starts chasing 2 hikers. Lock both begin running for their lives, but then among them stop to put on his running shoes.

His friend says, “What room you doing? You can not outrun a bear!”

His friend replies, “I don’t need to outrun the bear; ns only need to outrun you!”

If both friends room trying to gain away from the bear and also you discover that one of them is fast, go this information tell you that gets eaten? No! It only matters which one is faster, or rapid relative come the other. Relative elasticity is the same. In fact, us cannot pass judgement if one is elastic or inelastic unless we space referencing to another.

The concept of family member elasticity is not based on the calculations in 4.1 and also 4.2, as each need curve has actually an inelastic, elastic and unit elastic region.Demand curves take it the form of anything between perfectly elastic and perfectly inelastic, and also you have the right to only judge family member elasticity in reference to other curves.

What about Supply

The very same concepts and principles deserve to be used to supply. There is fairly far-reaching variation throughout different industries, with some relatively much more elastic than others.

Factors that InfluenceRelative Elasticity

So what causes this difference in family member elasticity? because that the many part, external determinants which influence responsiveness.


Availability of substitutes

The access of substitutes is a strong factor in determining the elasticity of a good. If there are plenty of close substitutes, thenit is fairly easy for consumer to uncover a suitable different to a good if prices rise.

necessity of a good

In addition, the degree to i m sorry a good is a necessity or a luxury considerably influences that elasticity. Essentials, such together soap, flour, sugar, etc. Are usually purchased in the same quantity regardless the price. ~ above the various other hand, consumer are an extremely price conscious when it involves luxury products (such together comforts, jewelry, etc.).


The necessity of a great depends quite greatly on the customer’s income. Someone with low income could be more price aware (elastic)when to buy a new sofa compared to someone with greater income. Generally the larger percentage of your income a good takes up, the more sensitive you will certainly be to price changes.


What reasons supply come be an ext or less elastic?

ease of access of resources

If a company’s manufacturing is dependent on scarce resources, the company is much less responsive to changes in price. Even if prices space high and the firm desires to rise production, it wont have the ability to without the proper inputs.

technological innovation

Innovation often tends to command to an ext efficient production. If a firm benefits from optimal notch manufacturing technology, it will be an ext able come respond to an increase in price with rise in production.

Barriers to entry

If there are couple of barriers come entry in an industry, an increase in price can reason a big increase in manufacturing as brand-new firms quickly enter the market.

Time: The Ever-Constraining Factor

Both the elasticity that supply and demand are influenced by time. Because that the consumer, exactly how much time they have to make a usage decision. For the producer, how much time it has actually to produce the good and develop inventory. Nevertheless of even if it is we are talking about supply or demand, rise in time always increases the elasticity that a an excellent by raising the capability to act and make informed decisions.


Whereas tough labels such together elastic, unit elastic, and also inelastic have the right to be supplied to describe details sections the supply and demand curve (based top top a calculate value), once comparing two curves everything is relative. Using the knowledge of perfect elasticity and also perfect inelasticity, we deserve to compare two curves top top the basis of elasticity come determine exactly how responsive the general consumer group, industry, etc. Is come price changes. Aflatter curve is relatively much more elastic than a steeper curve. Ease of access of substitutes, a goods necessity, and also a consumers income all affectthe loved one elasticity that demand. The accessibility of resources, technical innovation, and thebarriers come entry all impact the family member elasticity that supply. Time influence elasticity of either curve.

Now the we have the devices of supply, demand and also elasticity, we will usage them to recognize how government policy influence the market.


Perfectly Elasticthe exceptionally elastic case of need or supply wherein quantity transforms by an boundless amount in response to any change in price; horizontal in appearancePerfectly Inelasticthe extremely inelastic situation of need or it is provided in i m sorry a percentage change in price, no matter just how large, results in zero adjust in the quantity; vertical in appearance

Exercises 4.3

1. i beg your pardon of the adhering to does NOT impact the size of own-price elasticity of demand?

a) The size of the moment horizon end which we room looking at the adjust in consumer behaviour.b) The availability (or lack thereof) of nearby substitutes because that the good in question.c) The amount by which quantity gave will adjust as price changes.d) every one of the above affect the own-price elasticity the demand.

2. If a demand curve is VERTICAL, then own-price elasticity of demand for this great is equal to:

a) Infinity.b) Zero.c) One.d) nobody of the above.

3. If – given customer preferences – a certain good has many close substitutes available, then:

a) The need for that an excellent will be reasonably inelastic, compared to goods for which over there are couple of close substitutes.b) The it is provided of that great will be reasonably inelastic, compared to items for which over there are few close substitutes.c) The need for that good will be reasonably elastic, compared to items for which there are few close substitutes.d) The it is provided of that great will be reasonably elastic, contrasted to items for which there are few close substitutes.


See more: Solution: Mary Who Is Sixteen Is Four Times As Old As Her Brother

If – given customer preferences – a certain great has few close substitutes available, then:

a) The need for that good will be fairly inelastic, compared to items for which there are many close substitutes.b) The supply of that an excellent will be fairly inelastic, contrasted to goods for which there are countless close substitutes.c) The need for that great will be fairly elastic, compared to items for which there are countless close substitutes.d) The it is provided of that an excellent will be reasonably elastic, contrasted to products for which over there are countless close substitutes.