Measuring National Income (Cambridge (CIE) A Level Economics): Revision Note
Exam code: 9708
The meaning of national income
National income is the total monetary value of all goods and services produced by an economy over a given time period, typically one year
It measures the flow of income generated by economic activity — including wages, profits, rent and interest earned by factors of production
National income can be measured using three equivalent approaches, each of which should give the same result:
Output (production) approach
Value added at each stage of production across all sectors
Income approach
The sum of all factor incomes: wages, profits, rent and interest
Expenditure approach
The total spending on final goods and services: C + I + G + (X − M)
Only final goods and services are counted
Intermediate goods are excluded to avoid double counting
Measurement of national income
Gross domestic product (GDP)
GDP is the total market value of all final goods and services produced within a country's geographical borders in a given time period, regardless of the nationality of the producer
A Japanese car factory operating in the UK contributes to UK GDP
Profits repatriated abroad by that factory are included in UK GDP but not UK GNI
Gross national income (GNI)
GNI measures the total income earned by a country's residents and businesses, regardless of where that income is generated
GNI = GDP + net income from abroad
Net income from abroad = income earned by residents overseas − income earned by foreign residents domestically
For countries with large numbers of citizens working abroad (e.g. the Philippines), GNI exceeds GDP
For countries hosting many foreign-owned firms that repatriate profits (e.g. Ireland), GDP exceeds GNI
Net national income (NNI)
NNI adjusts GNI by subtracting capital depreciation - the loss in value of the capital stock through wear and tear over the period
NNI = GNI − depreciation (capital consumption)
NNI is a more accurate measure of a nation's sustainable income — it shows what is left after replacing worn-out capital
GDP and GNI are described as gross because they make no allowance for depreciation; NNI is net because depreciation has been deducted
The relationships between measures
Measure | Formula | What it excludes |
|---|---|---|
GDP |
|
|
GNI |
|
|
NNI |
| — |
Worked Example
Which source of income is not included in measuring real GDP?
A Pension paid to retired people
B Profits made by firms
C Rent paid to landlords
D Wages paid to nurses
Answer: A — pension paid to retired people [1]
Worked solution:
GDP measures the value of output produced in the economy - it counts incomes earned in return for productive activity:
Profits (B) — earned by firms in return for organising production ✓
Rent (C) — earned by landlords in return for providing land or property ✓
Wages (D) — earned by workers in return for labour supplied ✓
Pensions (A) — a transfer payment: no good or service is produced in return. The recipient is not contributing to current output - the pension is simply a transfer of income from taxpayers to retirees
Transfer payments are excluded from GDP because including them would count the same income twice — once when it was earned, and again when it is transferred.
Adjustments
1. Adjustment from market prices to basic prices
National income at market prices includes indirect taxes and subsidies in the valuation of output
It reflects what consumers actually pay
National income at basic prices (factor cost) removes the distortion of government intervention to show what producers actually receive
Indirect taxes are added to the price consumers pay
They must be subtracted to move from market prices to basic prices
Subsidies reduce the price consumers pay below what producers receive
They must be added back to move from market prices to basic prices
The adjustment:
GDP at basic prices = GDP at market prices − indirect taxes + subsidies
This adjustment matters because indirect taxes and subsidies distort market prices away from the true cost of production
Basic prices give a cleaner measure of the value added by producers
2. Adjustment from gross to net values
Gross measures (GDP, GNI) include the full value of investment spending, including the portion that simply replaces worn-out capital
They make no allowance for depreciation
Net measures (NNI) subtract capital consumption (depreciation) from gross values
Depreciation represents the fall in value of the capital stock due to wear and tear during the production process
Net measures therefore show the income available after maintaining the existing capital stock
NNI = GNI − capital consumption (depreciation)
Net measures are considered more meaningful for assessing sustainable living standards
A country with high gross output but very high depreciation has less true income available than the gross figure suggests
Worked Example
The information in the table is taken from a country's national income accounts.
$ million | |
|---|---|
Consumer expenditure | 250 |
Investment expenditure | 100 |
Government expenditure | 150 |
Exports | 100 |
Imports | 150 |
Taxes | 80 |
Subsidies | 40 |
What is the value of national income at factor cost in $ million?
A. 410
B. 450
C. 500
D. 550
Answer: A — 410
Worked solution:
Step 1 — Calculate GDP at market prices using the expenditure method
GDP at market prices = C + I + G + (X − M)
= 250 + 100 + 150 + (100 − 150)
= 450
Step 2 — Adjust from market prices to factor cost
GDP at factor cost = GDP at market prices − indirect taxes + subsidies
= 450 − 80 + 40
= 410
Why subtract taxes and add subsidies?
Indirect taxes are added to the price consumers pay, pushing market prices above what producers actually receive. Subsidies do the opposite - they allow goods to be sold below the cost of production. To find what producers truly earn (factor cost), taxes must be removed and subsidies added back.
The common trap is stopping at Step 1 and selecting B (450) - this is GDP at market prices, not at factor cost. Always check whether the question asks for market prices or factor cost before finalising your answer
Examiner Tips and Tricks
Keep the chain of adjustments in order: GDP → GNI → NNI. GDP adds no adjustment for where income is earned or for depreciation. GNI adds net income from abroad. NNI then subtracts depreciation. Each step moves closer to a measure of sustainable national income.
For market prices to basic prices: subtract taxes, add subsidies. Taxes inflate market prices above what producers receive; subsidies deflate them. Factor cost reflects what producers actually earn — it is the correct base for measuring the productive value of output.
The most common MCQ trap is transfer payments — pensions, unemployment benefit and student grants are all excluded from GDP because no output is produced in return. Only incomes earned through productive activity count.
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