GDP and GNP — Comprehensive Notes

GDP and GNP — Comprehensive Study Notes

6.1 Gross Domestic Product (GDP)

Macroeconomics studies economy-wide phenomena (e.g., inflation, unemployment, growth) and starts with the country’s total income and expenditure.
GDP is the total market value of all final goods and services produced within a country in a given period.
- Key phrase: market value. GDP aggregates many products into a single value, usually in the country’s currency. Non-market activities (e.g., household chores done for oneself) are excluded.
- GDP is measured within a country’s borders, regardless of whether output is produced by citizens or foreigners located there.
- GDP measures production that occurs in a specific interval of time (usually one year).
- GDP includes currently produced goods, not goods produced in the past; unsold inventories are included in the year they are produced.
- GDP includes tangible goods and intangible services (e.g., clothes, cars vs. haircuts, doctor visits).
What is excluded from GDP (limitations of scope):
- Non-market activities (household work, barter).
- Underground/illegal or unreported activity (e.g., drug trafficking) and unpermitted legal activity (e.g., workers without proper permits).
- Secondhand sales and financial transactions (e.g., selling a stock or bond).
- Transfer payments (e.g., retirement benefits, unemployment benefits) are not included in GDP.
- Intermediate goods to avoid double counting; GDP counts final goods and uses either the final-sales approach or the value-added approach.
- Quality changes and changes in the composition of goods can affect interpretation of GDP as a welfare measure.
- Imports are subtracted when calculating net exports; the value of imported goods is not included in domestic GDP.
Final goods vs. intermediate goods
- Final goods are consumed by the ultimate user; intermediate goods are used up in the production of final goods.
- Example: If a car is produced, the tires and dashboard are typically considered intermediate goods and are not counted separately towards GDP.
- To avoid double counting, GDP counts final goods or uses the value-added approach.
Methods to compute GDP (two broad approaches):
- Expenditure approach: GDP = C + I + G + NX
- Income approach: GDP = Wages + Salaries + Rental + Interest + Dividends + Profits
- In principle, both approaches yield the same GDP because every expenditure by a buyer is income for a seller.
Expenditure approach details
- C = Consumption expenditures by households; broken down into:
- Durable goods (e.g., automobiles, furniture, electrical items)
- Nondurable goods (e.g., fruits, vegetables, dairy, bread)
- Services (e.g., legal advice, medical treatment, education)
- I = Investment expenditure, consisting of:
- Fixed investment (capital equipment, structures such as factories, offices, houses)
- Inventories investment (goods produced but not yet sold)
- G = Government expenditures on goods/services and investment in equipment/structures (federal, state, local)
- NX = Net exports = Exports − Imports
- Transfer payments are not included in GDP under the income/expenditure accounting because they do not correspond to production.
Example to illustrate GDP components (Expenditure approach concept)
- Example: Malaysia’s economy with final goods only (erasers, bananas, shoes)
- GDP = (4 × RM0.25) + (6 × RM0.50) + (3 × RM20) = RM64
- Example: A haircut
- If the barber reports income to the government, it is counted in GDP; if a friend cuts hair and does not report, it is not counted.
Value-added and the production process
- GDP can be computed as the sum of value added at each stage of production:
- Value added at a stage = Value leaving the stage − Cost entering the stage
- Bread production example (four stages):
- Stage 1: Wheat to farmer; sale to miller for RM400; value added = RM400
- Stage 2: Mill to flour; sale to baker for RM600; value added = RM600 − RM400 = RM200
- Stage 3: Baker to bread; sale to shops for RM800; value added = RM800 − RM600 = RM200
- Stage 4: Shops to consumers; final bread price RM900; value added = RM900 − RM800 = RM100
- Total value added = RM400 + RM200 + RM200 + RM100 = RM900 (the final price equals sum of value added across stages)
GDP composition and categories
- Tangible goods vs. intangible services
- GDP measures currently produced goods, within borders, over a period
- Gastive example: final goods price often equals the sum of value added across stages
Real vs. Nominal GDP (economic growth interpretation)
- Nominal GDP: GDP measured at current year prices (not adjusted for inflation).
- Real GDP: GDP adjusted for inflation, using prices from a base year to allow comparison across years.
- Example calculation (Pizza and Latte):
- Yearly data (nominal): 2015: 10 × 400 + 2 × 1000 = RM6,000; 2016: 11 × 500 + 2.5 × 1100 = RM8,250; 2017: 12 × 600 + 3 × 1200 = RM10,800
- Real GDP with 2015 as base year:
 - 2015: 10 × 400 + 2 × 1000 = RM6,000
 - 2016: 10 × 500 + 2 × 1100 = RM7,200
 - 2017: 10 × 600 + 2 × 1200 = RM8,400
- Real GDP growth isolates changes in quantities, holding base-year prices fixed; nominal GDP growth can reflect price changes as well as output changes.
- Summary formulas:
- Nominal GDP in year t: $ext{Nominal GDP}t = \sumi pt^{(i)} qt^{(i)}$
- Real GDP in year t (base year b): $ext{Real GDP}t = \sumi pb^{(i)} qt^{(i)}$
- Real GDP can also be linked to a price index (GDP deflator): $ext{Real GDP}t = \frac{ ext{Nominal GDP}t}{P_{deflator,t}}$ where the deflator uses base-year prices.
Summary: What GDP tells you
- GDP measures two things simultaneously: total income and total expenditures; these are equal in a closed accounting sense: $ext{Total Income} = ext{Total Expenditures}$
- GDP per year reflects production within the country and can be decomposed into the four components (C, I, G, NX) or into income components (wages, rent, interest, profits).
Uses of National Income (GDP) beyond measurement
- Standard of living comparison: comparing living standards across countries or over time within a country
- Economic performance over time: tracking growth or stagnation
- National planning: informing short-term and long-term economic plans and forecasts
- Sectoral contributions: identifying which sectors drive growth
- Economic policy: shaping policy decisions using national income statistics
Limitations of GDP (detailed)
- Does not measure income distribution
- Does not measure non-monetary output or transactions (e.g., barter, household production, voluntary work)
- Secondhand sales are not included
- Does not account for changes in the quality of goods and services
- Does not include illegal activities (e.g., drug trafficking) or unreported production/sales
- Does not include transfer payments
- Selling financial assets (stocks/bonds) does not add to GDP
- Does not include the value of intermediate goods (to avoid double counting)
- GDP does not include goods produced in the past
- The value of imported goods is not included in GDP (imports are subtracted in net exports)
6.2 Gross National Product (GNP)
GDP vs GNP (definitions)
- GDP: the total market value of all final goods and services produced within a country in a given period (production within borders).
- GNP: the total market value of all final goods and services produced within a given period by factors of production owned by a country’s citizens, regardless of where the output is produced.
Relationship between GDP and GNP (illustrative examples)
- If a US-owned plant is located in China and earns profits there, those profits are included in US GNP but not in US GDP.
- If a Canadian-owned plant is located in the US and earns profits there, those profits are included in US GDP but are subtracted from US GNP.
- Both GDP and GNP are measures of economic activity, but their values can differ substantially depending on cross-border income flows.
- A compact way to express the relation:
- Let NFIA denote net factor income from abroad (income residents earn from abroad minus income foreigners earn domestically).
- Then: $ext{GNP} = ext{GDP} + ext{NFIA}$
Additional notes on national income accounting
- The two main approaches yield the same GDP value due to accounting identities; one can be used to cross-check the other.
Quick reference: key equations
- Expenditure approach:
 $ext{GDP} = C + I + G + NX$
 where $NX = X - M$ and $X = ext{exports}, ext{ } M = ext{imports}$
- Income approach:
 $ext{GDP} = ext{Wages} + ext{Salaries} + ext{Rental} + ext{Interest} + ext{Dividends} + ext{Profits}$
- Value added at a stage:
 $ext{Value added}_{ ext{stage}} = ext{Value leaving stage} - ext{Cost entering stage}$
- Real vs Nominal GDP (conceptual):
 $ext{Real GDP}t = ext{Nominal GDP}t ext{ adjusted for inflation}$
 or, using base-year prices,
 $ext{Real GDP}t = \sumi p^{(base)}i q^{(t)}i$
- GDP deflator (linking nominal to real):
 $ext{Nominal GDP}t = ext{Real GDP}t \times P_{deflator,t}$
Quick example recap prompts
- Example 1 (GDP components): Malaysia: 4 erasers at RM0.25, 6 bananas at RM0.50, 3 pairs of shoes at RM20 each → GDP = RM64.
- Example 2 (income reporting): Economic activity is counted only if reported and verifiable for tax purposes; unreported income is not included.
- Bread production stages: Demonstrates the value-added method across stages summing to final price.
- Nominal vs Real GDP example with pizza and latte illustrates the influence of price changes vs quantity changes on growth interpretation.
Final takeaways
- GDP is a powerful indicator of market activity and production within a country, but it has important limitations as a measure of welfare or standard of living.
- GNP complements GDP by accounting for the ownership of factors of production (citizens vs. foreigners) and whether production occurs abroad.
- Understanding the two primary accounting frameworks (expenditure vs income) helps interpret macroeconomic performance from different perspectives.

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