Q.What is sectoral composition of an economy? Is it necessary that the service sector should contribute maximum to GDP of an economy? Comment.

Sectoral Composition of Economy

Think of a country's economy like a large household. In a household, different members do different things — one person grows vegetables, another works in an office, a third runs a small shop from home. The total income of the household comes from all these activities combined. Now scale that up to a nation of millions, and you get the sectoral composition — the breakdown of the economy into its major activity groups.

The Three Sectors

Every economy's production can be classified into three broad sectors based on the nature of the activity:

Primary Sector — activities that directly extract or harvest natural resources. Agriculture, fishing, forestry, mining, and quarrying belong here. This is the oldest sector; it feeds people and supplies raw materials.

Secondary Sector — activities that transform raw materials into finished goods. Manufacturing, construction, electricity generation, and gas/water supply fall here. This is the industrial sector — factories, building sites, power plants.

Tertiary Sector — activities that provide services rather than goods. Trade, transport, banking, insurance, education, healthcare, tourism, IT services, and government administration. This is the service sector.

The Composition: What It Tells Us

The sectoral composition is simply the share of each sector in the economy's total output (GDP) and total employment. For example, if agriculture contributes 15% of GDP but employs 45% of the workforce, that tells you something important — low productivity in the primary sector.

You can express this as:

Where $i$ stands for primary, secondary, or tertiary. The same formula works for employment shares.

Why It Matters: The Structural Transformation Story

Here is the key insight that makes this concept powerful. As an economy develops, its sectoral composition changes in a predictable pattern — economists call this structural transformation.

A poor, underdeveloped economy has a very high share of the primary sector (often 50–70% of GDP and 70–80% of employment). People are mostly farmers. As development begins, the secondary sector's share rises — factories open, construction booms. Eventually, in a mature developed economy, the tertiary sector dominates (often 60–75% of GDP), while primary falls to under 5%.

India's own story illustrates this. At independence in 1947, agriculture contributed over 50% of GDP. Today, it contributes around 15–18% of GDP, yet still employs about 40–45% of the workforce. The tertiary sector now contributes over 55% of GDP — but employs far fewer people proportionally. This mismatch between sectoral shares in GDP and employment is a central challenge in Indian economic development.

Visualising the Concept …