Supply, Demand, and Market Equilibrium Study Guide

Foundational Mechanisms: In every market, price is established at the intersection of consumer desires and producer offerings. This interaction of supply and demand determines both the price and quantity of goods traded.
Price Volatility Examples: * Global Oil Prices: Prices can shift rapidly due to market factors. In October 2014, the price of oil was approximately $\text{£}90$ per barrel. By the end of December 2014, it had dropped to roughly $\text{£}55$ . * Seasonal Goods: The price of flowers rises significantly in the days preceding Mother's Day due to increased demand. * Service Premiums: Taxi drivers often double their rates on Christmas Day and New Year's Eve, reflecting extreme shifts in supply and demand conditions.

Definition of Equilibrium Price: The price at which the quantity demanded by consumers matches the quantity supplied by producers ( $D = S$ ). At this point, the wishes of consumers are met exactly by the output of producers.
The Market Clearing Price: Equilibrium is also referred to as the market clearing price. This is because: * The total amount supplied is completely purchased. * No consumers are left without the goods they want at that price. * No sellers are left with unsold stock.
Graphical Representation (Figure 1: Button Mushrooms): * Equilibrium Price ( $P$ ): $\text{£}1.50$ * Equilibrium Quantity ( $Q$ ): $60,000\,\text{kilos}$ * Mechanism of adjustment: If the price were set at $\text{£}2$ , producers would want to supply $80,000\,\text{kilos}$ , but consumers would only demand $40,000\,\text{kilos}$ because the price is too high.

Definition: Total revenue (TR) is the total amount of money generated from selling a specific quantity of output.
Formula: $TR = P \times Q$
Case Study Calculation (Mushroom Market): * Price ( $P$ ): $\text{£}1.50$ * Quantity ( $Q$ ): $60,000$ * $TR = \text{£}1.50 \times 60,000 = \text{£}90,000$

Increases in Demand: * Producers react to rising consumer interest by increasing prices. * Graphical effect: The demand curve shifts to the right (from $D$ to $D_1$ ). * Equilibrium Change: The price rises from $P$ to $P_1$ and the quantity traded rises from $Q$ to $Q_1$ . * Example: Gas-fired BBQs (2014): Due to one of the warmest summers on record in the UK, demand for BBQs soared, shifting the demand curve to the right.
Decreases in Demand: * Producers are forced to lower prices to avoid being left with unsold stock when consumer demand falls. * Graphical effect: The demand curve shifts to the left (from $D$ to $D_2$ ). * Equilibrium Change: The price falls to $P_2$ and the quantity falls from $Q$ to $Q_2$ .

Increases in Supply: * Occurs when producers are able or willing to provide more of a product at every price level. * Graphical effect: The supply curve shifts to the right (from $S$ to $S_1$ ). * Equilibrium Change: The price is forced down from $P$ to $P_1$ and the quantity sold increases from $Q$ to $Q_1$ . * Example: UK Hotel Accommodation: The opening of new hotels in a city increases the supply of rooms. In a provided example (Figure 5), the supply shift from $S$ to $S_1$ forces the price per room down from $\text{£}60$ to $\text{£}40$ , while the number of rooms let increases from $20,000$ to $25,000$ .
Decreases in Supply: * Graphical effect: The supply curve shifts to the left (from $S$ to $S_2$ ). * Equilibrium Change: The price rises from $P$ to $P_2$ and the quantity traded falls from $Q$ to $Q_2$ .

Complex Interactions: It is possible for both curves to shift at once. For example, demand may increase (right shift) while supply decreases (left shift).
Resulting Equilibrium (Figure 6): * A significant increase in demand paired with a decrease in supply will result in a higher new equilibrium price ( $P_1$ ). * The effect on quantity ( $Q$ ) is indeterminate unless the precise scale of the shifts is known. If the increase in demand is greater than the decrease in supply, quantity could also rise; however, Figure 6 shows a case where quantity falls from $Q$ to $Q_1$ .

Excess Demand (Shortage): * Occurs when the market price is set below the equilibrium price. * Mushroom Example: If price is set at $50\,\text{p}$ (below the $\text{£}1.50$ equilibrium), demand is $100,000\,\text{kilos}$ but supply is only $20,000\,\text{kilos}$ . * Calculation of Shortage: $\text{Shortage} = 100,000 - 20,000 = 80,000\,\text{kilos}$ .
Excess Supply (Surplus): * Occurs when the price is set above the equilibrium price. * Mushroom Example: If price is set at $\text{£}2.50$ , demand is only $20,000\,\text{kilos}$ while supply is $100,000\,\text{kilos}$ . * Calculation of Surplus: $\text{Unsold Goods} = 100,000 - 20,000 = 80,000\,\text{kilos}$ .

Fixed Supply Dynamics: When the supply of a good is limited and cannot be increased, the supply curve is vertical.
Wembley Stadium Capacity: The capacity is fixed at $90,000$ seats.
The Black Market: Because the English FA sets ticket prices lower than equilibrium to keep them "reasonably priced" (e.g., face value of $\text{£}60$ ), a shortage is created. * Equilibrium Price: Estimated at $\text{£}100$ per ticket in the example. * Shortage Size: At the $\text{£}60$ price point, demand is for $140,000$ seats, resulting in an excess demand of $50,000$ ( $140,000 - 90,000$ ). * Resale Values: Touts on the illegal black market may sell these $\text{£}60$ tickets for $\text{£}500$ or more.

Context: The construction industry was severely impacted by the 2008 financial crisis.
Sector Performance: * 2008: Output fell faster than the general economy. * 2009: The sector recovered faster than the general economy. * 2010-2011: Growth was flat. * 2012: The sector contracted again. * 2013: The sector grew through the year. * 2014: The sector remained $11.6\%$ below its 2007 peak.

Directional Flow: Demand curves should always slope downwards from left to right. Supply curves should slope upwards from left to right, except in instances of fixed supply (vertical curves).
Axis Labeling: Vertical axis represents Price ( $P$ ). Horizontal axis represents Quantity demanded and supplied ( $Q$ ). Examinations often award marks specifically for correct units and labels.

Equilibrium Price: The price where supply and demand are equal.
Excess Demand: Position where demand exceeds supply at a given price, causing shortages.
Excess Supply: Position where supply exceeds demand at a given price, causing unsold stock.
Total Revenue: Total amount of revenue generated from sales ( $P \times Q$ ) over a specific period.