National income statistics

Gross Domestic Product (GDP) is the total value of goods and services produced within a country's borders in a year, regardless of who owns the resources. It measures economic activity by location, so the output of a foreign-owned factory operating in the country is included.

Gross National Income (GNI) is derived from GDP by adding net primary income from abroad: GNI = GDP + net primary income from abroad. Net primary income from abroad is the income a country's residents earn from their assets abroad (profits, interest, dividends) minus the income foreigners earn from their assets within the country. So GNI measures the income of a country's residents wherever it is earned. If residents earn more abroad than foreigners earn domestically, GNI > GDP; if foreign-owned firms send large profits abroad, GNI < GDP.

Net National Income (NNI) is derived from GNI by subtracting depreciation (capital consumption): NNI = GNI − depreciation. Depreciation is the value of the capital stock (machinery, buildings) that wears out or becomes obsolete during the year. Because some of a country's investment merely replaces worn-out capital, subtracting depreciation gives the net addition to the economy's wealth.

So the chain is: GDP (output within borders) → add net income from abroad → GNI (income of residents) → subtract depreciation → NNI (net income of residents). GDP and GNI are 'gross' because they include replacement investment, while NNI is a true net measure but is harder to calculate because depreciation is difficult to measure accurately.

The figures need careful interpretation before they reveal much about performance.

Nominal vs real. GDP rose from $400bn to $440bn, a nominal rise of 10% ($40bn ÷ $400bn). However, inflation was 8%, so most of this increase is due to higher prices, not more output. Real GDP growth is only about 10% − 8% = 2%, so the economy grew only modestly in real terms. Judging performance by the nominal figure alone would be misleading.

GDP vs GNI. Because Country Y hosts many foreign-owned firms, much of the profit generated within its borders is sent abroad to foreign owners. This means its GNI is likely to be lower than its GDP (net primary income from abroad is negative). So GDP overstates the income actually available to Country Y's residents; GNI would be a better guide to their living standards.

Conclusion. Real growth of around 2% suggests modest improvement in output, but the gap between GDP and GNI means the benefit to residents may be smaller than the GDP figure implies. To assess performance properly we would also need GDP per head and information on the distribution of income.

GDP measures the total value of output produced within a country's borders. It is widely used as a proxy for living standards, but it has significant limitations.

The case for GDP. GDP (especially real GDP per head) gives a broad, regularly-measured indicator of the average material output and income available to a population. Higher real GDP per head usually means more goods and services per person, which tends to be associated with better food, housing, healthcare and education — genuine components of living standards. It is also widely available, allowing comparisons over time and (with PPP adjustment) between countries. As a first approximation, rising real GDP per head does tend to track rising material welfare.

The limitations. GDP is an average that ignores the distribution of income — a high GDP per head can coexist with widespread poverty if income is very unequal. It ignores non-marketed output such as household and informal-sector activity, which is large in developing economies, so it understates their true output. It takes no account of negative externalities (pollution, congestion, resource depletion) generated by production, which reduce welfare. It ignores leisure time and the quality of goods, and says nothing about non-material aspects of living standards such as health, freedom, security and the environment. Furthermore, GNI may be more appropriate where there is heavy foreign ownership, and nominal GDP must be converted to real terms to be meaningful.

Judgement. GDP is a useful but incomplete measure of living standards. Real GDP per head, PPP-adjusted, is a reasonable indicator of material living standards and a sensible starting point, which is why it is so widely used. However, it is not sufficient on its own, because it ignores distribution, externalities, the informal sector and non-material welfare. The most defensible conclusion is that GDP should be used alongside broader indicators — such as the Human Development Index, measures of inequality, and environmental indicators — to give a fuller picture. GDP is therefore a good partial measure but a poor complete one.

GDP measures output produced within a country's borders, while GNI measures the income of a country's residents (GDP + net primary income from abroad). When the question is the welfare of residents, the ownership of income matters, which is where GNI has an advantage.

The case for GNI being better. GNI captures the income that actually accrues to residents. In a country with many foreign-owned firms, a large part of the output counted in GDP is profit sent abroad, so GDP overstates the income available to residents; GNI (which subtracts this outflow) gives a truer picture of their welfare. Conversely, a country whose residents own many overseas assets earns income from abroad that GDP misses but GNI includes. So for measuring residents' command over goods and services, GNI is conceptually more appropriate.

The case against / qualifications. The difference between GDP and GNI is small for many countries, so in practice GDP is often an adequate proxy and is more readily available and timely. Moreover, both measures share the same fundamental weaknesses as welfare indicators: they ignore the distribution of income, non-marketed output, externalities and non-material aspects of welfare. Switching from GDP to GNI corrects only the foreign-income issue, not these deeper problems. Both also need to be expressed in real, per-head, PPP-adjusted terms to compare welfare validly.

Judgement. GNI is conceptually the better measure of residents' income/welfare, and noticeably better for countries with large foreign ownership or large overseas assets, because it reflects the income residents actually receive rather than where output is produced. However, the improvement is limited: where net income from abroad is small, GDP and GNI give similar results, and neither fully captures welfare because both ignore distribution, externalities and non-material factors. The most defensible conclusion is that GNI is the more appropriate measure of residents' income, and should be preferred where foreign income flows are large, but for a full welfare comparison it must still be real, per-head, PPP-adjusted and supplemented by wider indicators.