Wednesday, 22 June 2011

Aggregate Demand & Supply (Macroeconomics)

A classic AD/AS diagram has two axis. On the y axis (vertical one) we have price levels. Reading of this axis we will be able to see if the price levels in the economy have increased or decreased, thus seeing if there's been inflation or deflation in the economy. On the x axis (horizontal one) we have real GDP. The real part just means the figure has been adjusted slightly so it's in line with inflation. From the axis we will be able to read off the GDP of the economy so we can determine whether the economy has grown or shrunk. Also, we can determine from this axis whether unemployment has risen or fallen.

When we bring both aggregate demand and aggregate supply together and model them on the same diagram the two curves cross. This point is know as the macroeconomic equilibrium. This means both aggregate demand and aggregate supply are equal. 3 of the Governments's main objectives are to achieve full employment, low and stable inflation and to achieve steady economic growth. All of these can be viewed on an AD/AS diagram. Here is a standard AD/AS diagram:

As you can see, the AD curve hits the LRAS curve at the point where the LRAS curve begins to become vertical. This means that full employment has been achieved, or thereabouts. If AD was to shift to the left, it would mean unemployment has increased and the government would have to attempt to stimulate aggregate demand again to increase employment. It would do this by increasing any of the factors... (AD = C+I+G+(X-M)).

The government set the Bank of England the objective of stable prices (a target of 2% inflation). For this to be achieved, aggregate demand must not exceed the point of full employment on the diagram. If this would happen, you can see that price levels would increase dramatically and price levels rising is inflation.

To achieve economic growth, the AD curve would need to shift to the right - meaning Real GDP will have increased. To achieve this growth without inflation, the LRAS curve would need to shift to the right as well as the AD curve if the economy was operating at full employment. This would create some extra capacity for the economy to expand into.

There you have the three government objectives displayed and explained on a diagram. That's it for AD/AS diagrams.. Refer back to the individual posts about aggregate demand or aggregate supply if you're confused. Next up will be a short introduction to the multiplier effect. Thanks.