1. College of Business – Rabigh
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FINA 353 Principles of Macroeconomics Lecture 7 Topic: Aggregate Supply
College of Business – Rabigh
Dr. Mazharul Islam
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2. Learning outcomes for student revision
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Learning outcomes for student revision
To learn about
After studying these topics you should be able to:
Understand the meaning and factors that affect Aggregate Supply (AS or SAS)
Explain the meaning and differences between Equilibrium output (Ye) and Potential output (YP) and why and how they will change
Show changes using an AS graph and explain their output and price implications
the long run is normally a period of sufficient length such that everything is variable. The long-run is defined as the period when input prices have completely adjusted to changes in the price level of final goods. In the long-run, the increase in prices that sellers receive for their final goods is completely offset by the proportional increase in the prices that sellers pay for inputs.
while the short run is defined as a period when some things are variable while others are fixed.
Dr. Mazharul Islam
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3. Aggregate Supply
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Aggregate Supply is the total amount of final goods (G) and services (S) that firms in the country plan on selling during a specific time period.
The aggregate quantity of G&S supplied depends on 5 factors → quantity of labour (L ), Land and natural resources, Entrepreneurial talent, quantity of capital (K ), technology (T )
Dr. Mazharul Islam
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4. Aggregate Supply
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Aggregate Supply shows the relationship between the price level and quantity of real GDP supplied.
Short-run Aggregate Supply (SAS) is the relationship between the quantity of real GDP supplied and the output price level when factor prices (and potential GDP) are constant.
In the short-run: As prices rise producers are willing to increase quantity supplied (move along SAS) and employ more labour.
Dr. Mazharul Islam
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5. Quantity of real GDP supplied Price level ( GDP Price Index )
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SAS
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Other things remaining the same, the higher the price level, the greater the quantity of real GDP supplied , and the lower the price level, the smaller the quantity of real GDP supplied.
Quantity of real GDP supplied
Trillions of 2005 dollars
Price level ( GDP Price Index )
2005=100 P
14.0
120 E
13.5
115 D
13.0
110 C
12.5
105 B
12.0
100 A
Dr. Mazharul Islam
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6. Changes in Aggregate Supply in Short Run.
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125
SAS
115
105 95 85
Real GDP
860
880
900
920
940
Dr. Mazharul Islam
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7. Why the AS Curve Slopes Upward?
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The answer is:
If the price level rises , firms will increase the quantity of labor employed and the level of production (assuming money wages constant). Why?
To change its output rate, a firm must change the quantity of labor that it employs. If the additional labor costs less than the revenue the firm generates, it is profitable to hire more labor otherwise unprofitable.
Dr. Mazharul Islam
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8. Why the AS Curve Slopes Upward?
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So if the price level rises and the money wage rate doesn’t change (real wage rate decreases)  an extra hour of labor becomes profitable and both the quantity of labor demanded and production increase.
If the price level falls, firms will decrease the quantity of labor employed and the level of production (assuming money wages constant). Why?
If the price level falls and the money wage rate doesn’t change (real wage rate increases)  an extra hour of labor becomes unprofitable and both the quantity of labor demanded and production decrease.
Dr. Mazharul Islam
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9. What is Real Wage Rate?
Real wage rate shows how much the money wage rate buys goods and services.
The Real Wage Rate= the money wage rate divided by the price level ( GDP price index)
If the money wage rate denoted by W and,
If the price level denoted by P
Then;
Dr. Mazharul Islam

10. Why the AS Curve Slopes Upward?
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So if the price level rises relative to wages, profits increase, the number of firms in business increase, and the quantity of real GDP supplied as well as employment increases.
And if the price level falls relative to wages, profits decrease, the number of firms in business decreases, and the quantity of real GDP supplied as well as employment decreases.
Dr. Mazharul Islam
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11. Changes in SAS (Shift of the SAS curve)
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Changes in SAS (Shift of the SAS curve)
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Aggregate supply changes when any influence on production plans other than price level changes.
Aggregate supply changes when:
Potential GDP changes (economic growth).
The money wage rate changes.
The money prices of other resources change.
Changes in aggregate supply are not caused by changes in the price level of final goods and services.
Dr. Mazharul Islam
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12. Changes in SAS (Shift of the SAS curve)
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Changes in SAS (Shift of the SAS curve)
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Change in Potential GDP
Anything that changes potential GDP changes aggregate supply and shifts the aggregate supply curve.
If potential GDP increases then potential GDP line and SAS curve shift to the right.
Increase resources-Positive economic growth-AS increase- AS curve shift rightward.
Decrease resources-Negative economic growth-AS decrease-AS curve shift leftward.
Dr. Mazharul Islam
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13. Dr. Mazharul Islam Initial new Price Potential GDP Potential GDP Level
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Initial new
Price Potential GDP Potential GDP
Level
SAS SAS
120
C C”
110
100 90
Real GDP Supplied
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14. Changes in SAS (Shift of the SAS curve)
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Changes in SAS (Shift of the SAS curve)
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Changes in Money Wage Rate
A change in the money wage rate (nominal wage) changes aggregate supply because it changes firm’s costs.
The higher the money wage rate, the higher are the firms’ costs and the smaller is the quantity that firms are willing to supply at each price level. It does not affect the potential GDP. An increase in money wage a leftward (upward) shift of SAS curve. In alternative situation, SAS shifts to the right (downward)
Dr. Mazharul Islam
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15. 100 90 0 11.5 12 13 14 15 Real GDP Price Potential GDP Level SAS1 SAS0
120
110
100 90
Real GDP
SAS1
SAS0 D
SAS2 C
Dr. Mazharul Islam

16. Changes in SAS (Shift of the SAS curve)
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Changes in SAS (Shift of the SAS curve)
Change in Money Prices of Other Resources
A change in money prices of other inputs/resources (such as Changes in world oil prices, Changes in the weather, Technological change) has the same effect on firms’ production plans as a change in the money wage rate. It changes firms’ costs.
If the money prices of other resources rise, the price level is the same, the real costs change and the quantity that firms are willing to supply decreases at each price level ( SAS shifts to the left ). In alternative situation, SAS shifts to the right.
Increase of input price-decrease AS-SAS curve shift leftward
Decrease of input price-increase AS-SAS curve shift rightward.
Dr. Mazharul Islam
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17. Movements along the aggregate supply curves
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Summary
Movements along the aggregate supply curves
If output prices change but input prices do not, we have a movement along the SAS curve.
If both output and input prices change at the same rate, then we have a movement along the LAS curve.
Shifts of aggregate supply curves
When anything other than a change in real GDP or price level, SAS curve itself shifts. Such as
Changes in prices of other resources (such as world oil)
Changes in the weather
Technological change
Nominal (money) wage rate
Potential GDP
Dr. Mazharul Islam
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18. Now it’s over for today. Do you have any question?
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Now it’s over for today. Do you have any question?
Dr. Mazharul Islam
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