• Delving into the Midpoint Method in Economics

  • Contrasting the Midpoint and Point Elasticity Methods

  • The Significance of the Midpoint Method

  • Midpoint Method Example

  • Summary

Home > Blog > What is Midpoint Method

What is Midpoint Method

Calculating the elasticity of demand often involves dividing the percent change in quantity demanded by the percent change in price. This approach, however, can produce varying results if the calculation is done from point A to B or vice versa. The midpoint method offers a resolution to this variability, providing a consistent measure of elasticity whether calculating from point A to B or B to A. This guide will explore the midpoint method in detail, perfect for those keen on understanding its application in economics.

Delving into the Midpoint Method in Economics

The midpoint method plays a crucial role in economics, especially when determining the price elasticity of supply and demand. Elasticity, in this context, refers to how much the quantity supplied or demanded is affected by changes in price or other determinants.

There are primarily two ways to calculate elasticity: using the point elasticity method or the midpoint method. The latter, also known as arc elasticity, leverages the average percent change in both price and quantity to ascertain elasticity.

Elasticity is essentially a measure of how responsive the quantity demanded or supplied is to variations in price.

By calculating the percent change in price and quantity using the midpoint or average of two points, the midpoint method effectively removes the ambiguity that might arise with other methods. This ensures a consistent calculation of the percent change, irrespective of the direction in which it is performed.

Consider two points, A and B, with values 100 and 125 respectively. Depending on the direction of calculation, the results can differ significantly:

\[ \frac {100}{125}=0.8 \ \ \ \hbox{versus} \ \ \ \frac{125}{100}=1.25\]

Applying the midpoint method and taking the average value (112.5) between the two points addresses this discrepancy.

An understanding of whether demand or supply is elastic or inelastic is crucial. Elasticity implies a significant change in quantity demanded or supplied in response to price changes, whereas inelasticity indicates little to no change. For a deeper insight into elasticity, including the Elasticity of Supply and Demand, continue exploring our resources.

Contrasting the Midpoint and Point Elasticity Methods

In this section, we'll juxtapose the midpoint method with the point elasticity method. While both approaches are employed to compute the elasticity of supply and demand, utilizing similar data, they differ significantly in how they determine the base value for calculation in the point elasticity method, which affects the interpretation of price increases or decreases.

Point Elasticity Versus Midpoint Method: The Formula for Point Elasticity

The point elasticity formula aims to measure elasticity across a demand or supply curve between two points by dividing the change in quantity or price by its initial value. This ratio helps in calculating the elasticity by dividing the percent change in quantity by the percent change in price. The formula is expressed as:

\[\hbox{Point Elasticity of Demand}=\frac{\frac{Q_2-Q_1}{Q_1}}{\frac{P_2-P_1}{P_1}}\]

For instance, consider the change in demand when the price of bread falls from $8 to $6, leading to an increase in quantity demanded from 200 to 275 units. Applying these values to the point elasticity formula gives:

\( \text{Point Elasticity of Demand} = \frac{\frac{275-200}{200}}{\frac{\$6-\$8}{\$8}} \)

\( \text{Point Elasticity of Demand} = \frac{0.37}{-0.25} \)

\( \text{Point Elasticity of Demand} = -1.48 \)

Ignoring the negative sign, as is common in economics, indicates an elasticity of 1.48, suggesting the demand for bread is elastic.

However, using the point elasticity method can yield different interpretations of market dynamics even for the same curve. Let's further explore how the midpoint method addresses this inconsistency.

Midpoint Method Versus Point Elasticity: Understanding the Midpoint Formula

The midpoint method also calculates the elasticity of demand or supply but does so using the average percent change. This method's formula is:

\[\hbox{Elasticity of Demand}=\frac{\frac{(Q_2-Q_1)}{(Q_2+Q_1)/2}}{\frac{(P_2-P_1)}{(P_2+P_1)/2}}\]

Rather than dividing the change by the initial value, the midpoint method divides it by the average of the two values, thus the midpoint. This guarantees consistent elasticity calculations regardless of whether prices are increasing or decreasing.

Applying the midpoint method to calculate the elasticity of demand for bales of hay with a price decrease from $25 to $10, which increased demand from 1,000 to 1,500 bales, we get:

\(\hbox{Elasticity of Demand}=\frac{\frac{(1,500-1,000)}{(1,500+1,000)/2}}{\frac{($10-$25)}{($10+$25)/2}}\)

\(\hbox{Elasticity of Demand}=\frac{0.4}{-0.86}\)

Considering the absolute value, the demand for bales of hay is inelastic, as the elasticity is less than 1.

Re-evaluating the elasticity with a price increase from $10 to $25 demonstrates the consistency of the midpoint method:

\(\hbox{Elasticity of Demand}=\frac{\frac{(1,000-1,500)}{(1,000+1,500)/2}}{\frac{($25-$10)}{($25+$10)/2}}\)

\(\hbox{Elasticity of Demand}=\frac{-0.4}{0.86}\)

The elasticity remains constant at -0.47, showcasing the method's reliability in providing uniform percentage changes in both price and quantity, irrespective of the direction of change.

This comparison underscores the midpoint method's advantage in offering consistent elasticity calculations, addressing the variability issue inherent in the point elasticity approach.

Understanding Elasticity: Inelastic vs. Elastic

When it comes to determining whether a good is elastic or inelastic, we look at the elasticity value. If the absolute elasticity value falls between 0 and 1, consumers are considered inelastic to price changes. On the other hand, if the elasticity value is greater than 1, consumers are elastic to price changes. A value of 1 indicates unit elasticity, where consumers adjust their quantity demanded proportionally.

The Significance of the Midpoint Method

The midpoint method is crucial in providing consistent elasticity values regardless of whether prices are increasing or decreasing. This is achieved by using the same denominator in both equations when calculating the percent change in value.

In economics, the concept of elasticity is crucial in understanding how changes in price affect the quantity demanded or supplied of a good or service. There are different methods to calculate elasticity, such as the midpoint method and the point elasticity method.

The midpoint method is particularly useful when dealing with changes in price and quantity that are not linear. It calculates the percent change in price and quantity by taking the average of the initial and final values. This method ensures that the elasticity value remains consistent regardless of whether the price increases or decreases.

On the other hand, the point elasticity method is more precise and is used to calculate elasticity at a specific point on a demand or supply curve. This method takes into account the slope of the curve at that point, providing a more accurate measure of elasticity.

Midpoint Method Example

Let's consider an example using the midpoint method. If the price of pick-up trucks increased from $37,000 to $45,000, and the quantity demanded decreased from 15,000 to 8,000, we can calculate the elasticity of demand using the midpoint formula:

\(\hbox{Elasticity of Demand}=\frac{\frac{(8,000-15,000)}{(8,000+15,000)/2}}{\frac{($45,000-$37,000)}{($45,000+$37,000)/2}}\)

After calculations, we find that the elasticity of demand for pick-up trucks is -3.05. This indicates that consumers are highly responsive to changes in the price of trucks.


The midpoint method offers a consistent approach to calculating elasticity across non-linear changes, ensuring reliable results regardless of price direction. While point elasticity provides precision at specific points, understanding both methods is crucial for informed economic decision-making in pricing and market analysis.

Related Posts

What is Business Planning

Explore the in-depth guide of business planning, including its definition, key elements, and step-by-step process.

Macbeth: Story, Characters, Summary & Themes Explained

Explore Shakespeare's tragic tale of Macbeth with our in-depth guide covering the story, characters, summary, themes and more.

What is Rotational Motion: An In-Depth Guide to Circular Dynamics

Discover the fundamentals of rotational motion in this detailed guide. Learn about the principles, types, and examples of objects in rotation

What Are Formal Regions in Geography

Explore the concept of formal regions in geography, including clear definitions and illustrative examples. Learn how these areas are defined by governmental, cultural, and physical boundaries.