Economic Terms – Study Notes for Goa Police Sub‑Inspector (SI)
Audience – Candidates preparing for the General Awareness & Current Affairs paper of the Goa Police Sub‑Inspector exam.
Depth – MIT‑level treatment: first‑principles derivations, rigorous reasoning, subtle edge‑cases, and a challenging problem for self‑assessment.
Format – Markdown, fully self‑contained, with tables, equations, and illustrative graphs (ASCII where necessary).
1. Introduction
Economic terms form the backbone of any public‑sector policy discussion. In a policing context, they help you interpret news about budget deficits, inflation, employment, trade, and financial crime. Mastery of the core concepts allows you to:
- Understand official statistics (GDP, CPI, etc.).
- Gauge the impact of fiscal/monetary policy on public order.
- Detect economic anomalies that may signal or exacerbate criminal activity (e.g., money‑laundering, loan‑shark networks).
2. Fundamental Micro‑Economics
| Term | Definition | Key Equations | Edge Cases |
|---|---|---|---|
| Opportunity Cost | Value of best forgone alternative. | No explicit formula; used in decision trees. | When alternatives are non‑quantifiable (e.g., moral choices). |
| Production Possibility Frontier (PPF) | Set of all efficient production combinations. | (Y = f(X)) with (f'(X) < 0) | Non‑convex PPFs (e.g., due to technological discontinuities). |
| Marginal Utility (MU) | Additional satisfaction from consuming one more unit. | ( MU = \frac{dU}{dQ} ) | Diminishing MU may fail in addictive goods. |
| Elasticity of Demand | Responsiveness of quantity demanded to price changes. | ( \varepsilon_d = \frac{dQ/Q}{dP/P} = \frac{dQ}{dP}\frac{P}{Q} ) | Zero elasticity for a necessity with no substitutes. |
| Cross‑Price Elasticity | Effect of price of good A on demand of good B. | ( \varepsilon_{AB} = \frac{dQ_B}{dP_A}\frac{P_A}{Q_B} ) | Negative for complements, positive for substitutes. |
| Income Elasticity | Effect of income on demand. | ( \varepsilon_I = \frac{dQ}{dI}\frac{I}{Q} ) | Giffen goods: negative income elasticity for inferior goods that are staple foods. |
Theoretical Underpinning
-
Utility Maximisation: ( \max_{x} U(x) ) s.t. ( \sum p_i x_i \leq I ).
First‑order condition: ( \frac{\partial U}{\partial x_i} = \lambda p_i ).
Result: Consumers allocate expenditure such that marginal utility per rupee is equal across goods. -
Cost‑Minimisation: ( \min_{x} \sum w_i x_i ) s.t. ( f(x) \geq y ).
First‑order condition: ( \frac{\partial f}{\partial x_i} = \mu w_i ).
Result: Firms choose input mix to minimise cost for a given output.
3. Macro‑Economics: Core Indicators
| Indicator | What It Measures | Formula | Typical Interpretation |
|---|---|---|---|
| Gross Domestic Product (GDP) | Total value of goods & services produced inside the country. | ( GDP = C + I + G + (X-M) ) (Expenditure approach) ( GDP = \sum_i P_i Q_i ) (Production approach) |
Positive GDP growth → expansion; negative → recession. |
| Gross National Product (GNP) | GDP + income earned by residents abroad – income earned by foreigners domestically. | ( GNP = GDP + \text{Rem. inflow} - \text{Rem. outflow} ) | Useful for income‑based analysis. |
| Net National Product (NNP) | GNP minus depreciation. | ( NNP = GNP - \text{Depreciation} ) | Real output after accounting for asset wear‑and‑tear. |
| Real GDP | GDP adjusted for price changes (inflation). | ( \text{Real GDP} = \frac{\text{Nominal GDP}}{CPI/100} ) | Reflects actual increase in production. |
| GDP Deflator | Price level of all domestically produced goods. | ( \text{Deflator} = \frac{\text{Nominal GDP}}{\text{Real GDP}} \times 100 ) | Broader than CPI, includes investment goods, exports. |
| Consumer Price Index (CPI) | Weighted average of |