< Macroeconomics



Consumption is:Edit

what households, not businesses, do. This involves expenditure on goods and services, such as petrol, shopping and a new fridge. However, consumption can be split down further into durable and non-durable purchases.

  • Durable purchases are those that are going to last a long time - often years! These include items like cars, cookers, and televisions. Fridges, cookers, washing machines etc. are all durable goods.
  • Non-durable purchases are those that only last for a short period of time and are 'used up'. A good example of this is going to the shops to buy food and drink.

The Importance of Consumption Every time you purchase food at the drive-thru or pull out your debit or credit card to buy something, you are adding to consumption. Consumption is one of the bigger concepts in economics and is extremely important because it helps determine the growth and success of the economy. Businesses can open up and offer all kinds of great products, but if we don't purchase or consume their products, they won't stay in business very long! If they don't stay in business, many of us won't have jobs or the income to buy goods and services. Consumption can be defined in different ways, but is best described as the final purchase of goods and services by individuals. The purchase of a new pair of shoes, a hamburger at the fast food restaurant or services, like getting your house cleaned, are all examples of consumption. It is also often referred to as consumer spending. Many topics in economics explore how the income of families and individuals affects consumption and spending habits.


The level of consumption in the economy is determined by:

1) Cost of CreditEdit

If credit becomes difficult, mainly through expense of interest rates, some households may postpone their credit financed purchases. There will be a reduction in consumption until circumstances change, i.e. accumulate more savings, or a fall in interest rates. on the other hand if accessing credit becomes less expensive household will increase their consumption

2) AssetsEdit

Most households appear to have target levels of assets/wealth at each stage of their life cycle. If assets fall unexpectedly, households will increase their saving and reduce consumption. This works in reverse for situations like a sudden increase in wealth.

3) Disposable IncomeEdit

Disposable income (income is often expressed as 'Y') is income after taxes. It is the amount of total income that can be spent with reasonable freedom by the household. Thus, disposable income is total income minus taxes (and sometimes also regarded as including other fixed payments, such as mortgage repayments). It is that income which can be 'disposed of' with near freedom.

4) ExpectationsEdit

Individuals' attitudes to the functionality of the economy effects the level of aggregate expenditure. For example, households increase purchases of consumer durables if they believe interest rates will remain low or job security improves, etc. Expectations are the source of both business and household economic indicators. Strictly speaking, an expectation is a leading economic indicator, since it predicts changes in an economy and changes occur before corresponding changes in the economy.

A leading indicator is an economic statistic that suggests transactions in the future. For example, building permits suggest construction activity in the near term, and hence the hiring of construction workers and purchases of building materials. Purchases of raw materials by manufacturing industries ordinarily suggest a level of likely production. Increases in either suggest increased activity; decreases suggest decreases in near-term activity. Stock prices fit this category because high prices for corporate stocks create the impression of wealth that spurs consumption.

A coinciding indicator ordinarily indicates activity at the time. It is often a defining characteristic of the economy such as payroll or sales volume.

A lagging indicator is a statistic that ordinarily follows economic changes. Unemployment rates are a prime example; decisions by most employers to hire workers follow increases in activity and the parallel decision to lay off workers follows decreases in activity.

5) TaxationEdit

A change in the level of taxation on income (income tax) will reduce the amount of disposable income available. Because of this, C could fall. However, if an equal or greater sum were given out in benefits to households, particularly to unemployed, then consumption could even rise. It is important to note that an increase in taxation will not necessarily cause a contraction in consumption. Further, if taxation and benefits were used to redistribute income/wealth from richer to poorer households, consumption might rise. This is because less wealthy households are more likely to spend a greater proportion of their disposable income than extremely rich individuals.

  • Consumption varies between about 40-60% of total expenditure depending on what type of economy you are in, and the period in the economic cycle it is currently at.

The Keynesian Consumption FunctionEdit

C = a + b(ΔY)
a = Autonomous Consumption

b = Marginal Propensity to Consume
Autonomous Consumption is the amount of income someone has to spend to survive (level of absolute need)
MPC is the fraction/proportion of the remaining income that is spent on consumption. In reality it represents the how much of your income you are willing to spend on goods and services, as opposed to saving it for difficult times in the future or for retirement. The MPC is affected by consumer confidence and interest rates as they affect the rate of return on savings.

MPC = {\Delta C \over \Delta Y}


Example 1

C = 50 + 0.5(Y)
B = C = Y
Y = 50 + 0.5(Y)
Y - 0.5(Y) = 50
0.5(Y) = 50
Y = 100

Example 2

C = 50 + 0.9(Y)
B = C = Y
Y = 50 + 0.9(Y)
Y - 0.9(Y) = 50
0.1(Y) = 50
Y = 500


Saving(S) is not part of A.E. due to it being a leakage, (we analyse it because it helps us determine consumption and impacts on Y levels). The savings function (S = Y - C) can be derived from the consumption function (c.f.).

S = -a + b(Y)

where b is the Marginal Propensity to Save(MPS)