Welcome to Price Elasticity of Demand (PED)!
Ever wondered why some shops can raise their prices and still keep all their customers, while others lose everyone the moment they add 10p to a price tag? That is exactly what Price Elasticity of Demand (PED) is all about!
In this chapter, we are looking at how sensitive consumers are to price changes. Understanding this helps businesses decide how much to charge to make the most profit. Don't worry if the math looks scary at first—we will break it down step-by-step!
1. What exactly is PED?
Price Elasticity of Demand (PED) measures the responsiveness of the quantity demanded for a product to a change in its price.
Think of it like a rubber band:
• If a product is elastic, it’s like a stretchy rubber band. A small pull (change in price) causes a big stretch (change in demand).
• If a product is inelastic, it’s like a thick piece of string. No matter how hard you pull (change the price), the demand barely moves.
Quick Review:
• Elastic = Very responsive to price.
• Inelastic = Not very responsive to price.
2. Calculating PED: The Step-by-Step Guide
To find the PED, we use this formula:
\( PED = \frac{\% \text{ change in quantity demanded}}{\% \text{ change in price}} \)
How to calculate percentage change:
If you've forgotten how to do percentage changes, just use this simple trick:
\( \% \Delta = \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \times 100 \)
Step-by-Step Example:
A coffee shop raises the price of a latte from £3.00 to £3.30. As a result, the number of lattes sold per day drops from 100 to 80.
Step 1: Calculate % change in Price
\( \frac{3.30 - 3.00}{3.00} \times 100 = +10\% \)
Step 2: Calculate % change in Quantity
\( \frac{80 - 100}{100} \times 100 = -20\% \)
Step 3: Put them into the PED formula
\( PED = \frac{-20\%}{10\%} = -2 \)
Important Tip: In Economics, PED is almost always a negative number because when price goes up, demand goes down (the Law of Demand). However, economists often ignore the minus sign and just look at the absolute value (e.g., they would just say the PED is "2").
3. Interpreting the Numerical Values
Once you have your number, what does it actually mean? Here is the cheat sheet:
Value is Greater than 1 (e.g., 1.5, 2, 10): Price Elastic
The % change in demand is bigger than the % change in price. Consumers are very sensitive.
Example: A specific brand of chocolate bar. If the price goes up, you just buy a different brand.
Value is Less than 1 (e.g., 0.2, 0.5, 0.8): Price Inelastic
The % change in demand is smaller than the % change in price. Consumers are not very sensitive.
Example: Petrol or life-saving medicine. You need it, so you'll pay even if the price rises.
Value is Exactly 1: Unitary Elasticity
The % change in demand is exactly the same as the % change in price.
Example: A 10% price rise leads to exactly a 10% drop in sales.
Value is 0: Perfectly Inelastic
Demand doesn't change at all when price changes. This is rare in the real world! (Think of a vertical demand curve).
Value is Infinity (\(\infty\)): Perfectly Elastic
Any tiny increase in price causes demand to drop to zero. (Think of a horizontal demand curve).
Key Takeaway: If the number is "big" (over 1), demand is "stretchy" (elastic). If it's "small" (under 1), demand is "stiff" (inelastic).
4. Factors Influencing PED (The "SPLAT" Mnemonic)
Why are some things elastic and others inelastic? Use the SPLAT mnemonic to remember the factors:
S – Substitutes: The more substitutes available, the more elastic demand is. If Twix gets expensive, you'll just buy a Mars bar.
P – Percentage of Income: If a product is very cheap (like a box of matches), demand is inelastic. If it’s expensive (like a new car), demand is elastic.
L – Luxury vs. Necessity: Necessities (milk, electricity) are inelastic. Luxuries (designer handbags, holidays) are elastic.
A – Addictiveness/Habit: Products like cigarettes or coffee tend to be inelastic because people "need" their fix regardless of price.
T – Time: In the short term, demand is inelastic because it takes time for people to find alternatives. In the long term, it becomes more elastic.
5. PED and Total Revenue
This is the part that business owners care about most! Total Revenue is the total money a firm receives from selling goods:
\( \text{Total Revenue (TR)} = \text{Price} \times \text{Quantity} \)
If a firm changes its price, what happens to its total money coming in? It depends on PED!
If Demand is Inelastic (Consumers don't care much about price):
• Increase Price \(\rightarrow\) Total Revenue Increases. (You lose a few customers, but the higher price from the remaining ones makes up for it).
• Decrease Price \(\rightarrow\) Total Revenue Decreases.
If Demand is Elastic (Consumers are very sensitive):
• Increase Price \(\rightarrow\) Total Revenue Decreases. (So many customers leave that you lose money overall).
• Decrease Price \(\rightarrow\) Total Revenue Increases. (You attract so many new customers that your total money goes up).
Memory Trick:
Inelastic = Identical movement (Price and Revenue go the same way).
Elastic = Enemies (Price and Revenue go opposite ways).
6. Significance to Firms: Mass vs. Niche Markets
Firms use PED to set their Pricing Strategies.
Mass Markets:
Firms in mass markets (like supermarkets) often face elastic demand because there is so much competition. They usually use competitive pricing or penetration pricing (low prices) to attract large numbers of customers and increase total revenue.
Niche Markets:
Firms in niche markets (like luxury watchmakers) often have more inelastic demand because their products are unique or have high brand loyalty. These firms can use premium pricing or price skimming because they know their customers won't run away just because the price goes up.
Did you know? Airlines use PED to change prices constantly. They know business travelers have inelastic demand (they have to travel), so they charge them more for last-minute flights!
Summary: Quick Review Box
1. Formula: \( PED = \% \Delta Q / \% \Delta P \).
2. > 1: Elastic (Responsive).
3. < 1: Inelastic (Unresponsive).
4. TR & Inelastic: Price and Revenue move together.
5. TR & Elastic: Price and Revenue move in opposite directions.
6. Main Factor: The availability of substitutes is the biggest driver of PED.
Don't worry if this seems tricky at first! The best way to master PED is to practice the calculations until they become second nature. You've got this!