The four components of aggregate demand

Overview

Aggregate demand and write down its four components, consumption in the context of aggregate demand and net exports rather than exports alone appear in aggregate demand.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Define aggregate demand and write down its four components.

   Model answer

   Aggregate demand is the total planned spending on the goods and services produced within an economy at each general price level over a given period. It is made up of household consumption, investment by firms, government expenditure on goods and services, and net exports, so AD = C + I + G + (X - M). Because it is planned spending at each price level, it is a schedule rather than a single number.

2. 2

   What is consumption in the context of aggregate demand, and roughly how important is it?

   Model answer

   Consumption is household spending on goods and services, covering everything from food and fuel to holidays and haircuts, but excluding the purchase of new housing, which is classified as investment. It is by far the largest component in most developed economies, typically around two thirds of aggregate demand. Its size means that even small percentage changes in consumption move aggregate demand substantially.

3. 3

   What does investment mean when it appears as a component of aggregate demand?

   Model answer

   Investment is spending by firms on capital goods that will be used to produce future output: machinery, vehicles, buildings and software, together with additions to stocks of raw materials and unsold finished goods. Government spending on infrastructure is counted in G instead. It is spending on newly produced capital, not the purchase of existing assets. It is the most volatile component, because it depends heavily on expectations about the future.

4. 4

   Why is buying shares in a company not counted as investment in the aggregate demand sense?

   Model answer

   Buying shares transfers ownership of an existing financial claim from one person to another; no new capital good is produced, so nothing is added to output or demand for output. In economics the word investment is reserved for spending that creates new physical capital. Everyday usage of the word for saving in financial assets is a common source of confusion.

5. 5

   Which government payments count in the G component of aggregate demand, and which do not?

   Model answer

   Spending on goods and services counts: teachers' and nurses' salaries, medicines, road building, defence equipment. Transfer payments such as pensions, benefits and student maintenance do not, because the government receives no goods or services in return. Transfers affect aggregate demand only indirectly, when the households receiving them spend the money, at which point the spending appears as consumption.

6. 6

   Why do net exports rather than exports alone appear in aggregate demand?

   Model answer

   Aggregate demand measures demand for domestically produced output. Exports are foreign spending on domestic output, so they add to it. But the consumption, investment and government spending figures all include purchases of imported goods, which are demand for foreign output, so imports must be subtracted to avoid overstating demand for domestic production. The net figure, X minus M, is the trade sector's true contribution.

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