• An economic activity is the producing, purchase or selling of goods and services
• Economic activities can be grouped into four sectors:
  • Primary
  • Secondary
  • Tertiary
  • Quaternary

• Economic sectors are an indicator of a country's?economic development?using either:
  • The amount each sector contributes to the?Gross Domestic Product?(GDP)
  • The percentage of the population they employ
• The proportions of each economic sector GDP and employment changes over time:
  • In the?pre-industrial?period, the primary sector dominates with steady increases in the secondary and tertiary sectors
  • As countries develop the reliance on the primary sector for GDP and employment rapidly decreases
  • During the?industrial?period the amount of GDP and employment in the secondary sector increases to become dominant and then decreases. The primary sector continues to decrease and tertiary sector increases
  • In the?post-industrial?phase, the tertiary and quaternary sectors increase whilst the secondary and primary sectors decrease.
  • The tertiary sector dominates employment and GDP in the post-industrial period

The Clark-Fisher Model

Causes of Changes Over Time

• There are a number of reasons for the change in percentages employed in each sector:
  • Increasing?mechanisation?in agriculture led to a decrease in the jobs available
  • People moved to urban areas to find jobs in secondary and tertiary sectors
  • Increasing mechanisation and global changes led to a decrease in secondary employment in some countries
  • Technological improvements have led to an increase in tertiary and quaternary employment