Macroeconomics

Macroeconomics is the study of the economy viewed as a single interactive system. It is concerned, not with individual transactions, but with economy-wide aggregates including national income, the rate of inflation and the unemployment rate. At the theoretical level it seeks to explain how national income grows, how it fluctuates and what then happens to prices and unemployment. At the positive level it tests competing theories against the evidence provided by economic statistics, and it estimates the numerical relationships required to construct forecasting models. At the normative level it considers what policies would serve to promote economic stability and growth and full employment.

Since a national economy is too complex to analyse for those purposes, macroeconomics uses simplified versions, or “economic models” which ignore those components that are thought to have relatively little influence upon the question under consideration. The initial procedure postulates the way that the components of the system interact and deduces from those postulated relationships, how the system as a whole may be expected to behave. That deductive process is normally followed by the use of evidence and inductive reasoning to test, either the relationships themselves, or the deduced behaviour of the system.

The Main Macroeconomic Theories

The circular flow of income

The simplest theoretical model of a national economy is a system consisting of all of the country’s firms on the one hand, and all of its households on the other. National income in such a system is the total value of the firms’ output, which must be the same as the amount of money reaching the households in the form of wages interest and dividends (it has nowhere else to go). That money is then either saved, or spent on the firms’ products. The money reaching the firms consists of that spent by consumers and that invested (ie spent on the purchase of capital equipment from some of the firms). National income is thus both household spending plus savings and household spending plus investment. It follows, as a matter of arithmetic, that in such a system, savings must match investment. But in the economy as we know it, savings plans and investment plans are mostly made independently by different people. If the model is to represent what happens in such an economy, it must contain a mechanism by which planned investment is brought into line with planned savings

The classical model

Classical theory applies the market mechanism (which is described in the article on microeconomics) both to the problem of reconciling savings and investment plans, and to the operation of the labour market. It assumes that, in the market for savings, an excess of planned saving over planned investment would result in a reduction in the interest rate sufficient to bring the plans into line – and vice versa. In the market for labour, it assumes that if the planned demand for labour fell below the level required for full employment, wages would fall to a level at which full employment would be restored. The economy is thus assumed to have a self-righting capacity as regards both output and employment..

The Keynesian model

In the Keynesian model, planned savings are determined mainly by the level of income of the households. The adjustment mechanism by which a rise in planned saving would be brought into line with planned investment would be a fall in firms’ output - resulting in a sufficient fall in household income to reduce planned savings to equality with planned investment. And if the fall in output brought about a reduction in planned investment, there would be a further output reduction. The economy could settle into a stable condition in which output was below productive capacity. In the Keynesian model, moreover, the labour market does not have a self-righting capacity either, because wages are assumed to be “sticky downwards”, so the output fall would be accompanied by a rise in unemployment..