CoderKun's Tech Blog

Definition定义:

GDP is the market value of all final goods and services produced within a country in a given time period.

GDP（国内生产总值）是一个国家在特定时期内生产的所有最终商品和服务的市场价值总和。

Three Methods三种方法:

1. Production Approach生产法: Sum of value added by all industries计算各阶段附加值

2. Income Approach收入法: Wages + Profits + Rents + Interest + Indirect Taxes - Subsidies所有收入总和

3. Expenditure Approach支出法 ⭐: GDP = C + I + G + (X - M)

   • C = Consumption消费
   • I = Investment投资
   • G = Government Spending政府支出
   • X = Exports出口 / M = Imports进口

Key Terms | 得分关键词: market value, final goods, three methods, expenditure formula

Five Limitations五大局限性:

1. Non-Market Transactions非市场交易: Excludes household labor, volunteer work不包括家庭劳动、志愿者工作等

2. Income Distribution收入分配: Does not reflect income inequality不反映收入不平等

3. Informal Economy非正规经济: Excludes unregistered economic activities不包括未登记的经济活动

4. Quality of Life生活质量: Does not reflect environmental quality, leisure不反映环境质量、休闲时间等

5. Externalities外部性: Does not account for negative impacts like pollution不计入污染等负面影响

Key Terms | 得分关键词: non-market transactions, distribution, informal economy, quality of life, externalities

Formula公式:

Real GDP = Nominal GDP ÷ (Current Price Index ÷ Base Price Index)

Example例题: 2023年：名义GDP=$1500, CPI=150 (Base Year 2022基期2022: CPI=100)

Solution解答: Real GDP = 1500 ÷ 1.5 = $1000

Conclusion结论: Real GDP unchanged - welfare NOT improved! Nominal growth entirely due to inflation.实际GDP未变 - 福利未改善！名义增长完全由通胀造成。

Key Terms | 得分关键词: nominal vs real, price index, inflation adjustment

Formula公式: GDP = C + I + G + (X - M)

Example例题: C=$800B, G=$200B, X=$150B, M=$100B, GDP=$1200B

Find Investment (I) and Net Exports Ratio求投资(I)和净出口比率

Solution解答:

• I = 1200 - 800 - 200 - (150-100) = $150B
• Net Exports = 50B ÷ 1200 = 4.17%

Key Terms | 得分关键词: expenditure formula, component definitions, net exports

Formula公式:

Unemployment Rate = (Unemployed ÷ Labor Force) × 100%

Labor Force Participation Rate劳动力参与率: (Labor Force ÷ Working-Age Population) × 100%

Employment-Population Ratio就业人口比率: (Employed ÷ Working-Age Population) × 100%

Problems问题:

• May Understate可能低估: Discouraged workers not counted气馁工人未计入
• U-3 vs U-6官方失业率 vs 广义失业率

Key Terms | 得分关键词: labor force, participation rate, discouraged workers

Three Types三种失业类型:

1. Frictional摩擦性失业: Short-term, when workers transition between jobs工人在工作间转换的短期失业

2. Structural结构性失业: Skills mismatch with market demand, long-term技能与需求不匹配，长期

3. Cyclical周期性失业: Caused by economic recession经济衰退导致

Natural Rate自然失业率 = Frictional + Structural

Key Terms | 得分关键词: frictional, structural, cyclical, natural rate

Definition定义:

Maximizing satisfaction within budget constraints.在预算约束内最大化满足感。

Optimal Choice Condition最优选择条件:

MUa÷Pa = MUb÷Pb = … = MUn÷Pn

Marginal utility per dollar spent is equalized across all goods.每花费一美元的边际效用在所有商品上相等。

Law of Diminishing Marginal Utility边际效用递减规律: As consumption increases, marginal utility decreases.消费增加时，边际效用递减。

Key Terms | 得分关键词: utility, marginal utility, budget constraint, diminishing utility

Given已知: Income=$10, Price A=$1, Price B=$2收入=$10，产品A价格=$1，产品B价格=$2

Step 1: Calculate MU/P步骤1：计算MU/P

• A MU/P: 10, 8, 7, 6, 5
• B MU/P: 12, 10, 9, 8, 6

Step 2: Select in order of highest MU/P until budget exhausted步骤2：按MU/P从高到低选择，直到预算用完

Step 3: Find where MUa÷Pa = MUb÷Pb步骤3：找到MUa÷Pa = MUb÷Pb的点

Key Terms | 得分关键词: MU per dollar, equalization, budget exhaustion

Definition定义:

A market with few large firms controlling most market share, with high interdependence.少数几家大企业控制大部分市场份额，相互依存。

Four Characteristics四大特征:

1. Limited Number of Firms企业数量有限
2. Product Differentiation or Homogeneity产品差异化或同质化
3. High Barriers to Entry进入壁垒高 (economies of scale, capital, brands)(规模经济、资金、品牌)
4. Strong Interdependence相互依赖性强

Key Terms | 得分关键词: few firms, market share, interdependence, barriers to entry

I. Pricing StrategiesI. 定价策略:

1. Price Leadership价格领导: Leader sets price, others follow领导者定价，其他跟随
2. Price Discrimination价格歧视: Different prices based on willingness to pay根据购买意愿差异定价

II. Non-Pricing StrategiesII. 非定价策略:

1. Product Differentiation产品差异化
2. Advertising & Marketing广告与营销
3. R&D Investment研发投入

Key Terms | 得分关键词: price leadership, discrimination, differentiation, advertising

Eight Scenarios八种情况:

Memory Tip记忆技巧: Supply change → Price opposite direction; Demand change → Price same direction供给变化→价格反向；需求变化→价格同向

Key Terms | 得分关键词: curve shift, equilibrium, magnitude

I. Financial Markets (Direct Finance)I. 金融市场（直接融资）:

1. Bond Market债券市场: Certificate of indebtedness with maturity date & interest rate带有到期日期和利率的债务凭证
2. Stock Market股票市场: Partial ownership in firm企业部分所有权

II. Financial Intermediaries (Indirect Finance)II. 金融中介（间接融资）:

1. Banks银行: Take deposits, make loans吸收存款，发放贷款
2. Mutual Funds共同基金: Portfolio of stocks/bonds, professional management股票/债券组合，专业管理

Key Terms | 得分关键词: direct finance, indirect finance, bonds, stocks, banks

Definition定义:

Money is any asset people are willing to accept in exchange for goods/services or payment of debts.人们普遍愿意接受用于交换商品或偿还债务的任何资产。

Four Functions四大功能:

1. Medium of Exchange交易媒介
2. Unit of Account计价单位
3. Store of Value价值储藏
4. Standard of Deferred Payment延期支付标准

M1 vs M2M1与M2:

• M1 = Currency + Demand Deposits流通中的现金+活期存款
• M2 = M1 + Savings Deposits + Money Market Funds储蓄存款+货币市场基金

Key Terms | 得分关键词: four functions, commodity money, fiat money, M1, M2

Three Tools三大工具:

1. Open Market Operations公开市场操作 ⭐

   • Buy bonds → Money↑ → Interest↓ → Expansionary买债券→货币↑→利率↓→扩张
   • Sell bonds → Money↓ → Interest↑ → Contractionary卖债券→货币↓→利率↑→紧缩

2. Reserve Requirements准备金率

   • Lower ratio → Bank lending↑ → Expansionary降低→银行贷款↑→扩张

3. Discount Rate贴现率

   • Lower rate → Bank borrowing cost↓ → Expansionary降低→银行借款成本↓→扩张

Transmission Mechanism传导机制: Central Bank Action → Money Supply → Interest Rate → Investment/Consumption → GDP

Key Terms | 得分关键词: open market operations, reserve, discount rate, transmission

Definition定义:

Changes in federal taxes and government purchases to achieve macroeconomic objectives.通过改变税收和政府支出来实现宏观经济目标。

Types类型:

1. Automatic Stabilizers自动稳定器: Automatically change with business cycle自动随经济周期变化
2. Discretionary Policy相机抉择政策: Intentional government actions政府主动行动

Fiscal Policy Tools财政政策工具:

Key Terms | 得分关键词: automatic, discretionary, expansionary, contractionary

Government Purchases Multiplier Formula政府购买乘数公式:

Multiplier = 1 ÷ (1 - MPC)

where MPC = Marginal Propensity to Consume其中MPC=边际消费倾向

Example例题: MPC=0.5, ΔG=$100B

Solution解答:

• Multiplier = 1÷(1-0.5) = 2
• ΔY = 100 × 2 = $200B

Tax Multiplier税收乘数: Tax Multiplier = -MPC ÷ (1-MPC)

Key Conclusion关键结论: G multiplier > T multiplier (absolute value)G乘数 > T乘数（绝对值）

Key Terms | 得分关键词: multiplier, MPC, induced consumption, government purchases

Definition定义:

A decline in private expenditures as a result of an increase in government purchases.政府支出增加导致私人支出减少的现象。

Mechanism机制:

G↑ → Borrowing demand↑ → Money demand↑ → Interest rate↑ → Private Investment↓ + Consumption↓ + NX↓借款需求↑→货币需求↑→利率↑→私人投资↓ + 消费↓ + 净出口↓

Policy Implication政策启示: Fiscal policy effectiveness weakened by crowding out; requires monetary policy coordination财政政策效果被挤出效应削弱；需要货币政策配合

Key Terms | 得分关键词: crowding out, interest rate, investment, coordination

Regression Results on BRIC CountriesBRIC国家回归结果:

1. Private Credit (logCRED)私人部门信贷:

   • t-stat = 1.005 (NOT significant不显著, < 2)
   • Conclusion: Monetary policy NOT effective结论：货币政策效果不明显

2. Government Spending (logGSPE)政府支出:

   • t-stat = -0.951 (NOT significant不显著)
   • Conclusion: Government spending has little effect结论：政府支出作用不大

3. Tax Revenue (logTREV)税收收入 ⭐:

   • t-stat = -4.000 (SIGNIFICANT显著 > 2)
   • Conclusion: Taxation IS effective in reducing inequality!结论：税收有效减少不平等！

Significance Test显著性判断: |t-statistic| > 2 = significant显著

Key Terms | 得分关键词: t-statistic, significance, regression, policy effectiveness

Absolute Advantage (Adam Smith)绝对优势（亚当·斯密）:

• A country is more efficient (lower cost) at producing a good一个国家以更低成本生产商品

Comparative Advantage (David Ricardo)比较优势（大卫·李嘉图）:

• Even without absolute advantage, benefit from focusing on goods with lower opportunity cost即使没有绝对优势，也可通过专注于低机会成本的商品获益

Sources of Trade Benefits贸易利益来源:

• Specialization专业化
• Economies of scale规模经济
• Technology diffusion技术扩散

Key Terms | 得分关键词: absolute advantage, comparative advantage, opportunity cost, specialization

Types of Barriers壁垒类型:

1. Tariffs关税: Tax on imports进口税
2. Import Quotas进口配额: Quantity limit on imports进口数量限制
3. Non-Tariff Barriers非关税壁垒: Technical standards, sanitary measures, subsidies技术标准、卫生检疫、补贴

Welfare Effects of Tariffs关税的福利效果:

Key Terms | 得分关键词: tariffs, quotas, consumer surplus, deadweight loss

Seven Core Theories七大核心理论:

1. Creative Destruction (Schumpeter 1942)创造性破坏（熊彼特1942）: New models replace old ones continuously新模式持续取代旧模式

2. Network Effects (Katz & Shapiro 1985)网络效应（1985）: Value rises with number of users价值随用户数增加而增加

3. Knowledge Economy (Romer 1990)知识经济（罗默1990）: Knowledge & innovation drive growth知识与创新驱动增长

4. Winner-Takes-All (Arthur 1994)赢家通吃（1994）: Small advantages lead to long-term dominance小优势导致长期垄断

5. Skill-Biased Tech Change (Autor & Katz 1998)技能偏向型技术变革（1998）: Technology favors skilled workers技术偏向高技能工人

6. Platform Economy (Rochet & Tirole 2003)平台经济（2003）: Multi-sided markets with cross-side network effects多边市场，跨边网络效应

7. Zero Marginal Cost (Rifkin 2014)零边际成本（2014）: Digital goods cost almost nothing to reproduce数字产品复制成本几乎为零

Key Terms | 得分关键词: creative destruction, network effects, knowledge economy, zero marginal cost

Ten Major Issues十大主要问题:

1. Market Concentration & Big Tech Dominance市场集中度与大科技公司垄断
2. Data Privacy & Ownership数据隐私与所有权
3. AI & Automation人工智能与自动化
4. Digital Inequality (Digital Divide)数字不平等（数字鸿沟）
5. Gig Economy & Platform Labor零工经济与平台劳动
6. Platform Regulation平台监管
7. Digital Taxation数字税收
8. Cybersecurity网络安全
9. Digital Trade Barriers数字贸易壁垒
10. Environmental Sustainability环境可持续性

Key Terms | 得分关键词: market concentration, data privacy, digital divide, regulation

Lorenz Curve洛伦兹曲线:

• X-axis: Cumulative % of population轴：人口累计百分比
• Y-axis: Cumulative % of income轴：收入累计百分比
• 45° line = Perfect equality线 = 完全平等

Gini Coefficient基尼系数:

Gini = A ÷ (A + B)

• A = Area between Lorenz curve and 45° line洛伦兹曲线与45°线间面积
• B = Area below Lorenz curve洛伦兹曲线下面积
• Range: 0 (perfect equality) to 1 (perfect inequality)范围：0（完全平等）到1（完全不平等）

Government Redistribution Effect政府再分配效果: After taxes & transfers, Gini coefficient decreases税收和转移支付后，基尼系数降低

Key Terms | 得分关键词: Lorenz curve, Gini coefficient, redistribution

Seven Causes七大原因:

1. Ability能力差异: Innate abilities differ天生能力不同
2. Education & Training教育和培训: Human capital differences人力资本差异
3. Discrimination歧视: Gender, race, age discrimination性别、种族、年龄歧视
4. Preferences & Risks偏好与风险: Job preference and risk tolerance differences工作偏好和风险承受能力差异
5. Unequal Wealth Distribution财富分配不均: Inherited wealth, capital income differences继承财富、资本收入差异
6. Market Power市场力量: Monopoly, oligopoly, union power垄断、寡头、工会力量
7. Luck, Connections, Misfortune运气、关系和不幸: Birth family, networks, unexpected events出生家庭、社会网络、意外事件

Key Terms | 得分关键词: ability, education, discrimination, wealth, market power

Arguments for Equality支持平等的论点:

• Diminishing marginal utility: $1 to poor person > $1 to rich person边际效用递减：给穷人$1 > 给富人$1
• Income redistribution can increase total social utility收入再分配可以增加社会总效用

Arguments for Inequality支持不平等的论点:

• Income gaps provide work incentives收入差距提供工作激励
• Redistribution reduces savings and investment motivation再分配减少储蓄和投资动力

Trade-off权衡: Pursuing equality may sacrifice economic efficiency (leaky bucket experiment)追求平等可能牺牲经济效率（漏桶实验）

Key Terms | 得分关键词: diminishing utility, incentives, efficiency loss, trade-off

Formula公式:

PED = % Change in Quantity Demanded ÷ % Change in Price需求量变化 ÷ %价格变化

PED = (ΔQ÷Q) ÷ (ΔP÷P)

Example例题: Price rises from $10 to $12; Quantity demanded falls from 100 to 80价格从$10上升到$12；需求量从100下降到80

Solution解答:

• % ΔQ = (80-100)÷100 = -20%
• % ΔP = (12-10)÷10 = +20%
• PED = -20% ÷ 20% = -1.0

Interpretation解读: |PED| = 1 = Unit Elastic单位弹性

| |PED| | Type类型 |
|———|——–|
| > 1 | Elastic富有弹性 |
| = 1 | Unit Elastic单位弹性 |
| < 1 | Inelastic缺乏弹性 |

Key Terms | 得分关键词: elasticity formula, percentage change, elastic

Elasticity Application弹性应用:

Evaluate impact of agent banking outlets on social indicators评估代理银行网点对社会指标的影响

Formula公式: Elasticity = % Change in Dependent Variable ÷ % Change in Independent Variable因变量变化 ÷ %自变量变化

Analysis Results分析结果:

1. Literacy Rate Elasticity ≈ 0.02识字率弹性≈0.02:

   • < 1 (inelastic缺乏弹性)
   • Agent banking NOT effective for literacy代理银行对识字率效果不佳

2. Unemployment Rate Elasticity ≈ 1.76失业率弹性≈1.76:

   • 1 (elastic富有弹性)

   • But cannot conclude effectiveness due to other factors但由于其他因素无法得出有效性结论

Overall Conclusion总体结论: Agent banking is NOT effective in solving illiteracy and unemployment代理银行在解决识字和失业问题上效果不明显

Key Terms | 得分关键词: elasticity formula, effectiveness, policy evaluation