Differentiate between perfectly elastic and also inelasticUnderstand the difference in between elasticity ~ above a solitary curve and also relative elasticityExplain what variables influence elasticity that supply and demand
(Credit: college of Victoria Students’ Society)

Textbook or Burger?

In object 4.1 and 4.2, us looked at elasticity on a single demand curve and also examined just how responsive customer are to price changes at assorted levels of production. Yet what around responsiveness throughout firms? across industries? We recognize that in certain industries, such together the textbook industry, consumers are much less responsive to adjust than others. Just how is the quantity demanded for textbooks affected by boost in price? If the textbook for a course rose from $100 to $150, what would certainly you do? many students will buy the publication anyway, because it is a compelled course material. Publishers are increasingly using different strategies come ensure the sector stays inelastic or unresponsive to price change, such together bundling the textbook through mandatory course access codes. To compare this instance with the price of a burger. If the price the a citizens rises indigenous $8 come $12, you may purchase having lunch from a various restaurant or start packing having lunch from home. The market for textbooks and burgers are very different. In this section, we will discover the relative elasticity of various markets.

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 Perfectly Elastic and also Perfectly Inelastic

To begin the conversation about relative elasticity, it helps to first look at the extremes.

Perfectly Elastic

Imagine a product whereby if the price increased, also slightly, you i will not ~ buy any it anymore. Sound familiar? That’s due to the fact that we introduced this concept in subject 3, as one of the presumptions of a perfectly competitive market. One of the examples we used was identical hot dog stands, side by side, wherein the only distinction was price. If quality is the same, the rational consumer will constantly purchase the hot dog the is a lower price. Native the view of the stand, they recognize that if they boost price also slightly, they will offer 0 units. This method that ED = ∞.

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

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

We recognize that \frac\Delta Q\Delta P is equal to the inverse of the slope. In the need curve in figure 4.3a, as soon as the ΔP>0 then ΔQ is equal to ∞. This means that \frac\Delta Q\Delta P = ∞. 

Figure 4.3a

Perfectly Inelastic

At the other finish of the spectrum, take into consideration a sector where the firm can proceed to boost prices v no readjust in quantity. If you to be poisoned and also had to buy the antidote, would certainly you be responsive come price change? probably not. This is an instance of a situation where need is virtually perfectly inelastic. If you rise the price, amount demanded does not change. This means that ED = 0.

We deserve to confirm this by utilizing point-slope at any suggest in number 4.4a.

In the need curve in number 4.3a, once the ΔP>0 then ΔQ is same to 0. This method that \frac\Delta Q\Delta P = 0. 

Figure 4.3b

 Relative Elasticity

The ideas of perfect elastic and also perfectly inelastic lead us right into a discussion of family member elasticity. In 4.1 and 4.2, we examined a single demand curve, and also looked at the numerical value of elasticity follow me that demand curve. However, elasticity can additionally be helpful when comparing demand curves. Even though each demand curve has actually an inelastic, elastic, and also unit elastic section, the comparison of the curves can present which markets are relatively more responsive to price changes. This is an essential concept to understand for as soon as we look in ~ the effects of a plan change.

Figure 4.3c

Figure 4.3c illustrates two curves. One is relatively an ext inelastic and also the other is relatively more elastic. The best method to determine which is an ext elastic or inelastic is to to compare each curve come the extremes. The curve much more resemblant the perfect elasticity is relatively an ext elastic, the curve an ext resemblant or perfect inelasticity is relatively more inelastic. Keep in mind this is various than saying one is elastic and also the other inelastic! come emphasize this point, read the ar “Bears and also Elasticity.”

Bears and also Elasticity

(Credit: Wapster/ Flickr/ CC through 2.0)

A be afflicted with jumps the end of a bush and also starts chasing 2 hikers. They both begin running for their lives, but then one of them stops to placed on his running shoes.

His friend says, “What space you doing? You can’t outrun a bear!”

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

If both friends are trying to get away from the bear and also you find out that among them is fast, walk this information tell you who gets eaten? No! It only matters which one is faster, or fast relative come the other. Loved one elasticity is the same. In fact, us cannot happen judgement if one is elastic or inelastic uneven we are referencing to another.

The principle of relative elasticity is not based on the calculations in 4.1 and also 4.2, together each need curve has actually an inelastic, elastic and unit elastic region. Demand curves take it the form of anything in between perfectly elastic and perfectly inelastic, and you have the right to only judge loved one elasticity in recommendation to other curves.

What around Supply

The same concepts and principles deserve to be used to supply. Over there is fairly far-reaching variation throughout different industries, through some relatively more elastic 보다 others.

Factors that Influence Relative Elasticity

So what causes this distinction in loved one elasticity? because that the many part, external factors which affect responsiveness.


Availability that substitutes

The availability of substitutes is a strong factor in determining the elasticity the a good. If there are plenty of close substitutes, then it is relatively easy for consumers to find a suitable different to a great if prices rise.

requirement of a good

In addition, the extent to i m sorry a an excellent is a necessity or a luxury substantially influences its elasticity. Essentials, such as soap, flour, sugar, etc. Are typically purchased in the same amount regardless that price. Top top the other hand, consumers are very price aware when it involves luxury items (such together comforts, jewelry, etc.).


The need of a great depends quite heavily on the customer’s income. Someone through low income might be more price mindful (elastic) when to buy a brand-new sofa contrasted to someone with higher income. Normally the bigger percentage the your income a great takes up, the much more sensitive you will be come price changes.


What reasons supply to be more or much less elastic?

access of resources

If a company’s manufacturing is dependency on scarce resources, the firm is less responsive to changes in price. Also if prices are high and also the firm wants to rise production, that wont be able to without the appropriate inputs.

technical innovation

Innovation has tendency to lead to much more efficient production. If a firm services from peak notch production technology, it will certainly be more able to respond to rise in price with boost in production.

Barriers come entry

If over there are few barriers to entry in one industry, boost in price can cause a big increase in production as new firms easily enter the market.

Time: The Ever-Constraining Factor

Both the elasticity that supply and demand are affected by time. Because that the consumer, exactly how much time they need to make a usage decision. Because that the producer, exactly how much time it has to develop the great and develop inventory. Regardless of whether we room talking about supply or demand, rise in time constantly increases the elasticity the a an excellent by enhancing the capacity to act and make notified decisions.


Whereas hard labels such as elastic, unit elastic, and also inelastic deserve to be supplied to describe details sections that supply and demand curves (based top top a calculated value), once comparing two curves every little thing is relative. Using the expertise of perfect elasticity and perfect inelasticity, we deserve to compare 2 curves ~ above the communication of elasticity come determine how responsive the general customer group, industry, etc. Is come price changes. A flatter curve is relatively more elastic 보다 a steeper curve. Access of substitutes, a goods necessity, and a consumers earnings all affect the relative elasticity that demand. The ease of access of resources, technical innovation, and the barriers come entry all impact the relative elasticity of supply. Time influence elasticity of either curve.

Now that we have actually the tools of supply, demand and elasticity, us will use them to recognize how government policy affects the market.


Perfectly Elasticthe very elastic situation of need or supply wherein quantity alters by an unlimited amount in an answer to any change in price; horizontal in appearancePerfectly Inelasticthe extremely inelastic situation of demand or supply in which a percentage change in price, no matter exactly how large, outcomes in zero adjust in the quantity; upright in appearance

Exercises 4.3

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

a) The length of the moment horizon over which we space looking at the readjust in consumer behaviour.b) The ease of access (or absence thereof) of close substitutes for the great in question.c) The amount whereby quantity provided will readjust as price changes.d) every one of the over affect the own-price elasticity of demand.

2. If a need curve is VERTICAL, climate own-price elasticity of demand for this good is equal to:

a) Infinity.b) Zero.c) One.d) no one of the above.

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

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


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If – given consumer preferences – a certain good has couple of close substitutes available, then:

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