You will no doubt come across the 3 methods of calculating GDP that is in the macro syllabus of most courses. Here are the main features of each.
National Income measures the value of output produced within the economy over a period of time. One of the key economic objectives of government is to increase the level, and rate of growth, of national income. Before we start to analyse why economic growth is so important, it is important to be able to define the key concepts.
GROSS DOMESTIC PRODUCT (GDP)
Under new definitions introduced in the late 1990s, Gross Domestic Product is also known as Gross Value Added. It is defined as the value of output produced within the domestic boundaries of the NZ over a given period of time, usually a year. It includes the output of foreign owned firms that are located in NZ, such as the majority of Trading Banks in the market – ASB, National, ANZ etc. It does not include output of NZ firms that are located abroad. There are three ways of calculating the value of GDP all of which should sum to the same amount since by identity:
NATIONAL OUTPUT = NATIONAL INCOME = NATIONAL EXPENDITURE
1. THE EXPENDITURE METHOD
This is the sum of the final expenditure on NZ produced goods and services measured at current market prices (not adjusted for inflation). The full equation for calculating GDP using this approach is:
GDP = Consumer expenditure (C) + Investment (I) + Government expenditure (G) + (Exports (X) – Imports (M))
GDP = C + I + G + (X-M)
2. THE INCOME METHOD
This is the sum of total incomes earned from the production of goods and services. By adding together the rewards to the factors of production (land, labour, capital and enterprise), we can see how the flow of income in the economy is distributed. The rewards to the factors of production can be loosely summarised in the following table:
Land – Rent
Labour – Wages and Salaries
Capital – Interest
Enterprise – Profit
Only those incomes generated through the production of a marketed output are included in the calculation of GDP by the income approach. Therefore we exclude from the accounts items such as transfer payments (e.g. government benefits for jobseekers allowance and pensions where no output is produced) and private transfers of money.
The income method tends to underestimate the true value of output in the economy, as incomes earned through the black economy are not recorded.
3. THE OUTPUT MEASURE OF GDP
This measures the value of output produced by each of the productive sectors in the economy (primary, secondary and tertiary) using the concept of value added.
Value added is the increase in the value of a product at each successive stage of the production process. For example, if the raw materials and components used to make a car cost $16,000 and the final selling price of the car is $20,000, then the value added from the production process is $4,000. We use this approach to avoid the problems of double-counting the value of intermediate inputs. GDP will, therefore, be equal to the sum of each individual producer’s value added.
Problems of accuracy:
Officially data on a nation’s GDP tends to understate the true growth of real national income per capita over time e.g. due to the expansion of the shadow economy and the value of unpaid work done by millions of volunteers and people caring for their family members. There may also be errors in calculating the cost of living
The scale of the informal “shadow economy” varies widely across countries at different stages of development. According to the IMF, in developing countries it may be as high as 40% of GDP; in transition countries of central and Eastern Europe it may be up to 30% of GDP and in the leading industrialised countries of the OECD, the shadow economy may be in the region of 15% of GDP.
India’s cash economy
It is believed that in 2009 Indians held more money is Swiss banks than people from all other countries combined.
– A 2010 study by the World Bank has suggested that India’s shadow economy is equivalent to 20% of GDP.
– Research indicates that 85% of jobs in India are typically cash orientated.
– Only 42,800 people declare income of over 10m rupees a year – only 2.5% of Indians pay income tax.
Mumbai has a huge stock of empty apartments held as investments, their owners unwilling to to sell for fear that the proceeds might enter the formal economy and be taxed.
Source: The Economist. March 23rd 2013