Price elasticity of demand

Introduction: Why Should We Care About Price Elasticity?

Ever wondered why a cinema can charge a fortune for popcorn, but if the local supermarket raised the price of a loaf of bread by 50p, everyone would stop buying it? This isn't just luck—it’s Price Elasticity of Demand (PED).

In this chapter, we are going to explore how "sensitive" customers are to changes in price. For a business, knowing this is like having a superpower: it tells them whether they can raise prices to make more profit or if doing so will drive all their customers away. Don’t worry if the math seems tricky at first; we’ll break it down into simple steps that anyone can follow!

1. What exactly is Price Elasticity of Demand (PED)?

Price Elasticity of Demand measures how much the quantity demanded of a product changes when its price changes.

Think of it like a rubber band:

1. Elastic Demand: Like a stretchy rubber band. A small pull (price change) causes a big stretch (change in demand). Customers are very sensitive to price.
2. Inelastic Demand: Like a thick, stiff piece of string. You can pull it hard (big price change), but it hardly moves (small change in demand). Customers aren't very sensitive to price.

Quick Review: If a price change causes a huge reaction from customers, the demand is Elastic. If customers barely notice or keep buying anyway, it is Inelastic.

2. How to Calculate PED

To find the PED, we use a simple formula. You must remember to use percentage changes, not just the change in pounds or units!

The Formula:
\( PED = \frac{\% \text{ change in Quantity Demanded}}{\% \text{ change in Price}} \)

Step-by-Step Calculation:

Let's say a cafe sells 100 coffees a day at £3.00. They raise the price to £3.30, and sales drop to 80 coffees.

Step 1: Find the % change in Quantity.
\( \frac{\text{New Quantity} - \text{Old Quantity}}{\text{Old Quantity}} \times 100 \)
\( \frac{80 - 100}{100} \times 100 = -20\% \)

Step 2: Find the % change in Price.
\( \frac{£3.30 - £3.00}{£3.00} \times 100 = +10\% \)

Step 3: Put them into the PED formula.
\( PED = \frac{-20\%}{10\%} = -2.0 \)

Common Mistake to Avoid: Always put Quantity on top and Price on the bottom. A good way to remember this is "Q comes before P in the alphabet" (so Q is on top!).

Note: PED is almost always a negative number because as price goes up, demand goes down. In the exam, we often look at the "absolute value" (the number itself), so -2.0 is usually just referred to as 2.0.

3. Interpreting the Numbers

Once you have your result, what does it actually mean? Use this guide:

If the result is greater than 1 (e.g., 1.5, 2.0, 5.0):

The demand is Price Elastic. Customers are sensitive. A 10% price increase might lead to a 20% drop in sales.
Example: Luxury chocolates or a specific brand of cereal.

If the result is less than 1 (e.g., 0.2, 0.5, 0.8):

The demand is Price Inelastic. Customers are not sensitive. Even if the price goes up, people still need to buy it.
Example: Petrol, electricity, or addictive goods like cigarettes.

If the result is exactly 1:

The demand is Unitary Elastic. The change in demand is exactly the same as the change in price.

Memory Tip: Inelastic looks like the letter "I". If you were to draw an inelastic demand curve on a graph, it is very steep, just like the letter I!

4. Factors Influencing PED

Why are some things elastic and others inelastic? Here are the main factors:

• Availability of Substitutes: This is the biggest factor. If there are lots of other brands (like chocolate bars), demand is elastic. If there are no alternatives (like a specialized medicine), demand is inelastic.
• Necessity vs. Luxury: Things you need (milk, bread) tend to be inelastic. Things you want but can live without (a designer handbag) are elastic.
• Habit and Addiction: If a customer is brand-loyal or addicted (cigarettes), they will keep buying even if the price rises. This makes demand inelastic.
• Proportion of Income: If a product is very cheap (like a box of matches), a 10% price rise is only a few pennies—people don't care, so it’s inelastic. If it’s an expensive car, a 10% rise is thousands of pounds, so it’s elastic.
• Time: In the short term, demand is often inelastic because people haven't found an alternative yet. Over time, it becomes more elastic as they switch to other options.

Key Takeaway: The more choices a consumer has, the more Elastic the demand will be.

5. PED and Total Revenue

This is the part that business owners care about most! Total Revenue is the total money coming in from sales (\( \text{Price} \times \text{Quantity} \)).

The "Price Change Rule":

1. If demand is INELASTIC (Value < 1):
- If you Increase Price, Total Revenue Increases. (The extra money per sale makes up for the few lost customers).
- If you Decrease Price, Total Revenue Decreases.

2. If demand is ELASTIC (Value > 1):
- If you Increase Price, Total Revenue Decreases. (You lose so many customers that the extra price isn't worth it).
- If you Decrease Price, Total Revenue Increases. (You gain so many new customers that it makes up for the lower price per unit).

Did you know? This is why discount airlines like Ryanair keep prices low. Their demand is Elastic, so lowering the price slightly leads to a massive surge in passengers, increasing their total revenue!

6. Significance to Businesses

Why do students of 9BS0 need to know this? Because businesses use PED for Decision Making:

• Pricing Strategy: If a business knows their brand is strong and demand is inelastic, they might use Price Skimming (charging a high price).
• Sales Forecasting: Businesses can predict how much their sales will drop if they are forced to raise prices (e.g., due to a new tax).
• Impact of Branding: One goal of advertising is to make demand more inelastic. By building brand loyalty, businesses make customers less sensitive to price, allowing the business to charge more without losing sales.

Quick Review Box:
- Elastic: Sensitive to price (\( > 1 \)). Lower prices to raise revenue.
- Inelastic: Not sensitive to price (\( < 1 \)). Raise prices to raise revenue.
- Formula: % Change in Q / % Change in P.

Final Summary Takeaway

Understanding PED is all about balance. A business must weigh up the price they want to charge against the volume of sales they will lose. If you can identify *why* a customer might be sensitive (substitutes, necessity, etc.), you can master the concept of Price Elasticity of Demand!