The Short-run Macroeconomic Equilibrium

A very simplified Keynesian model is used to show the short-run macroeconomic equilibrium. For example, the rate of interest is fixed to simplify the model by keeping constant money in the economy. It is also assumed that production and employment depend on the amount of spending. In that we mean that if people buy more then firms will produce more, providing that they have the spare capacity available. The basic formula we use is that the level of National Income is equal to the domestic consumption plus the three withdrawals from the circular flow of income. Or, in shortened terms: Y = Cd + W. In this model, aggregate demand is actually known as aggregate expenditure (E) and relies on the amount of domestic consumption and the injections into the circular flow of income (J). Also written as AD = E = Cd + J. We reach a point of equilibrium when withdrawals equal injections and at this same point National Income will equal aggregate expenditure. If injections were to be higher than withdrawals then National Income would rise and the withdrawals would rise until withdrawals is once again equal to injections. Now enter the 45 degree line.

The 45 degree line shows the relationship between National Income and consumption, withdrawals and injections. Consumption and withdrawals are endogenous - their value is determined by the model. However injections are exogenous, meaning their value is determined independently of the model.

At ever point on the 45 degree line (Y), the items on each axis equal each other. The C line is consumption. It differs from Cd because it doesn't contain taxes and export spending. Consumption is a function of National Income: C = f(Y). As National Income rises, so does consumption - hence the upwards slope. It crosses the 45 degree line because poorer people may be required to spending above their earnings to survive where as richer people spend less than they earn, therefore at the end of the line it is below the Y line. The slope is given by the marginal propensity to consume - the proportion of any increase in National Income that goes on consumption. It is the change in consumption divided by the change in National Income. 

Consumption is determined by a whole bunch of different things: 

• Taxes
• Expected future incomes
• Expected future prices
• Consumer confidence
• Household wealth 
• Attitudes of the lenders
• Age of 'durables'
• Distribution of income

Any changes in these cause a shift in the consumption function whereas a change in National Income causes a movement along the consumption function. 

Now onto the withdrawals. The amount saved depends on the marginal propensity to save (mps). The proportion of an increase in National Income that is saved. Mps = Change in savings / Change in N.I. Taxes is pretty much the same - it depends on the marginal propensity to tax (mpt), or changes in tax / changes in N.I. It tends to rise as National Income rises because income tax is progressive. Finally imports - depending on the marginal propensity to import. Or, mpm = change in imports / change in National Income. 

Total withdrawals will look something like this: 

Injections now and we'll start with investment. It is determined by the following things: Consumer demand, expectations, interest rate, availability of finance and cost/efficiency of capital equipment. Replacing new equipment will rely on National Income. Government spending is independent of National Income in the short term, Exports is also classed as independent on National Income to keep the model simpler.  

That's it for the background on the theory. Next we'll be moving on to how National Income is determined from all of this. Stay tuned.

Sam. 

Monetary Policy (Macroeconomics)

Monetary policy, liked with fiscal policy is another tool the government can use to control the economy. Monetary policy involves the use of exchange rates, interest rates and the money supply to manage the economy.

Firstly, interest rates. These are set by the MPC and are mainly used in the U.K to try and achieve the inflation target of 2.0%. The theory is that a reduction in interest rates will give consumers more disposable income through lower loan repayments and this will boost the consumption factor of Aggregate Demand. Also, it should make businesses take out loans more willingly as borrowing money becomes cheaper and thus the investment factor of Aggregate Demand will rise also. Overall, a fall in in interest rates should create a rise in the real GDP of the country. It works the opposite way with a rise in interest rates, this should reduce the real GDP of the country as well as control inflation.

Interest rate changes also effect the Balance of Payments. Interest rates in the U.K. rising will cause a flow of 'hot money' into the economy as people will benefit from the higher returns of putting their money in the U.K. This flow will increase the demand for the pound, so the value will appreciate. The knock on effect of an appreciation in the value of the pound is that our exports become more expensive and it becomes cheaper for us to import goods. This will worsen the Balance of Payments. Obviously, the opposite will occur with a fall in interest rates.

Exchange rates was another tool under the title of 'Monetary Policy'. By managing the exchange rate, the Bank of England can buy and sell pounds to influence the exchange rate. This will control the competitiveness of U.K. exports and therefore help control the Balance of Payments. However, the government doesn't generally take this approach as they let the free market determine the value of the pound. One instance where this is sometimes done is in China.

The final tool under the 'Monetary Policy' heading was the money supply. This is where the government can increase or decrease the amount of money in the economy. The idea behind increasing the money supply is that it should stimulate Aggregate Demand as people have more money to spend and businesses have more money to invest. However, this method is very inflationary and is widely avoided. Decreasing the money supply will have the opposite effect to the above.

That's it, the three parts involved in the 'Monetary Policy' tool the government has at its disposal. Thanks for reading.

Aggregate Supply (Macroeconomics)

So, what is aggregate supply?
Well, aggregate supply is the total output of goods and services that producers in an economy are willing and able to supply at different price levels in a given time period. Aggregate supply can be modeled on a diagram in two ways: the long run and the short run.

In this diagram we have a long run aggregate supply curve, sometimes shortened to just 'LRAS'. We can see that initially supply increases as the price level increases as businesses stand to make more profit. The curve then hits at vertical point. This point is know as full employment. What this means is that all factors of production are fully employed so there can be no more growing. So, after this point the only change that occurs is the increase in price levels. The point of full employment is similar to operating on the edge of the PPC which was described in a previous post. The next post will go into further detail about the long run diagrams. 

Another way aggregate supply can be modeled is in the short run. 

Here we have aggregate supply in the short run, sometimes referred to as just 'AS'. In this the curve is simply sloping upwards as factors of production ca easily be increased or improved in the short run. The AS may increase (shift to the right on the diagram) if there are falls in production costs or a fall in wages. It may decrease (shift to the left on the diagram) if production costs increase or something like the price of oil increase. 

Going back to the long run aggregate supply curve now. It has the potential to shift if aggregate supply changes. 

The causes of changes in the LRAS curve are:

• A fall in interest rates. This will encourage businesses to invest therefore allowing them to expand and increase supply. This will shift LRAS to LRAS 1 on the diagram. If interest rates rose the opposite would happen and we could end up at curve LRAS 2 on the diagram.
• Unemployment related benefits could be reduced. This would encourage more to try and get back into work, thus giving more potential labour for firms. This will increase LRAS to LRAS 1. The opposite would happen if unemployment related benefits were increased.
• Education and training will improve the productivity of the workforce.. pushing LRAS out to LRAS 1. If funding for education and training was cut then LRAS may fall to curve LRAS 2.

That's pretty much it for a brief overview of aggregate supply. In the next post i'll be looking at aggregate supply and aggregate demand together and how these can be modeled on one diagram. Thanks for reading!