Introduction to Aggregate Supply (AS)
Welcome! In the previous chapter, we looked at Aggregate Demand—everything that people in an economy want to buy. Now, we are looking at the other side of the coin: Aggregate Supply (AS). This is all about the "sellers" or the firms in the economy.
Understanding Aggregate Supply is like understanding the "productive engine" of a country. We will explore how much businesses are willing to produce at different price levels and what makes them change their minds. Don't worry if it seems like a lot of graphs at first; we will break it down step-by-step!
What is Aggregate Supply?
Aggregate Supply (AS) is the total volume of goods and services produced within an economy at a given price level in a given time period. Essentially, it is the total Real GDP that all the firms in a country are willing and able to provide.
Quick Tip: While "Supply" in Microeconomics is about one business or one product, "Aggregate Supply" is the sum of every business in the country!
In Economics, we divide Aggregate Supply into two timeframes: 1. The Short Run (SRAS) 2. The Long Run (LRAS)
1. Short-Run Aggregate Supply (SRAS)
In the Short Run, we assume that at least one factor of production is fixed. Most importantly, we assume that wage rates and the prices of raw materials are fixed (they don't change immediately when the price level changes).
The Relationship Between Price Level and SRAS
The SRAS curve slopes upwards from left to right. This shows a positive relationship: as the general price level in the economy rises, the quantity of goods and services supplied also increases.
Why does it slope upwards?
Think of it this way: If the prices of the goods a firm sells go up, but their costs (like wages) stay the same, their profit margin increases. This encourages them to hire a few more workers or pay current workers overtime to produce more!
Shifts in the SRAS Curve
A "movement along" the curve only happens if the Price Level changes. However, the whole curve will shift if the costs of production change.
Factors that shift SRAS:
- Wage Rates: If workers demand higher wages, it costs more to produce goods, shifting SRAS to the left.
- Raw Material Prices: If the price of oil or electricity goes up, costs rise, and SRAS shifts left.
- Taxation on Firms: An increase in Business Rates or Corporation Tax acts like a cost, shifting SRAS left.
- Exchange Rates: If the currency gets weaker, imported raw materials become more expensive, shifting SRAS left.
Memory Aid: Think of W.O.T.E. (Wages, Oil/Raw Materials, Taxes, Exchange Rates). If these costs go UP, SRAS goes LEFT (decreases).
Quick Review: SRAS
- Upward sloping: Higher prices = more profit = more supply.
- Shifts: Caused by changes in the costs of production.
2. Long-Run Aggregate Supply (LRAS)
The Long Run is the period where all factors of production are variable. In the long run, we aren't just looking at profits; we are looking at the productive potential of the entire country.
The Relationship Between Price Level and LRAS
In the OCR syllabus, the LRAS curve is typically drawn as a vertical line. This represents the Full Employment level of output (often labeled as \(Y_f\) or \(Y_{p}\)).
Why is it vertical?
Economists argue that in the long run, the economy will always produce at its maximum capacity regardless of the price level. If all your factories are full and everyone has a job, you can't produce any more just because prices went up!
Analogy: Imagine a sponge. You can squeeze it to get a little more water out in the short run (SRAS), but the sponge only has a certain size (LRAS). To get more water in the long run, you need a bigger sponge!
Shifts in the LRAS Curve
The LRAS curve shifts when the quantity or quality of the factors of production (Land, Labour, Capital, Enterprise) changes. This is essentially Economic Growth.
Factors that shift LRAS to the right (Increasing Potential):
- Improvements in Technology: New inventions allow us to produce more with the same resources.
- Education and Training: A more skilled workforce is more productive.
- Increased Investment: More factories and better machines.
- Incentives: Government policies that encourage people to work harder or start businesses.
- New Resources: Finding new oil fields or a sudden increase in the working population (immigration).
Did you know?
When the LRAS shifts to the right, it is exactly the same concept as the Production Possibility Curve (PPC) shifting outwards! Both represent an increase in the maximum possible output of the economy.
Common Mistakes to Avoid
1. Confusing the axis: In Macroeconomics, the vertical axis is Price Level (not just "Price") and the horizontal axis is Real GDP or Output (labeled as \(Y\)).
2. Mixing up shifts: Remember, SRAS shifts because of costs (like oil prices). LRAS shifts because of capacity (like better technology).
3. The "Short Run" isn't a set time: In Economics, the "short run" isn't always "six months." It's simply however long it takes for wages to eventually change and catch up with prices.
Key Takeaways for Revision
- Aggregate Supply (AS) is the total output of the economy.
- SRAS is upward sloping because higher prices make production more profitable in the short term.
- SRAS shifts occur when the costs of production (wages, raw materials) change.
- LRAS is vertical, representing the maximum "productive potential" of the economy.
- LRAS shifts occur when the quality or quantity of resources improves (e.g., better education or tech).
- Rightward shift = Increase in supply; Leftward shift = Decrease in supply.
Don't worry if the distinction between the two curves feels a bit abstract. Just remember: SRAS = Costs; LRAS = Capabilities!