Economic Curves Simulator: 6 Key Models Including The Hockey Stick

This web app simulates six fundamental economic curves from Austrian and classical economics: (1) Armey Curve (government spending vs growth), (2) Laffer Curve (tax rates vs revenue), (3) J-Curve (economic shocks vs recovery), (4) Supply-Demand (market equilibrium), (5) Division of Labor (Adam Smith's Pin Factory), and (6) The Hockey Stick (capitalism's prosperity explosion). Adjust parameters to explore how policy, market forces, and economic freedom affect prosperity.

About the Armey Curve

The Armey curve is an economic model that describes the relationship between the size of government spending and economic growth. It posits that as government spending increases from zero, economic growth initially rises because essential public goods—like infrastructure, the legal system, and education—boost prosperity and stability. However, after reaching an optimal point, further increases in government size lead to diminishing returns, inefficiency, and crowding out of private investment, so economic growth then declines.

Curve Structure

The Armey curve is typically illustrated as an inverted U-shaped (parabolic) graph. On the horizontal axis is government spending (often as a percentage of GDP), and on the vertical axis is economic growth or societal welfare. The "peak" of the curve represents the optimal government size for maximum growth. Empirical research commonly situates this optimum between 20% and 30% of GDP, though the exact figure varies by country and time period.

Mathematical Formulation

The curve is often expressed with a quadratic equation:

Y = β₀ + β₁ · G + β₂ · G²

where Y is economic growth, G is government spending, and coefficients β₁ > 0, β₂ < 0 capture the concave shape—positive effects at first, negative effects after the turning point.

Understanding the Intercept (β₀)

The positive intercept value β₀ represents the natural growth rate without government intervention. This is the baseline economic growth rate that would occur when G = 0 (zero government spending), driven purely by private sector activity including:

  • Private sector dynamics: Businesses, entrepreneurs, and markets operating without government involvement
  • Natural productivity gains: Technological innovation, efficiency improvements, and capital accumulation driven by private actors
  • Spontaneous market coordination: Voluntary exchanges and market mechanisms that create value
  • Population growth effects: Demographic changes that contribute to economic expansion

In essence, β₀ represents the growth rate of a purely laissez-faire economy where all economic activity comes from private initiative, without any government provision of public goods, infrastructure, regulation, or spending. The rest of the curve then shows how government spending can initially enhance this natural growth (through beneficial public goods) before eventually hindering it (through inefficiencies and crowding out).

Policy Implications

  • An undersized government fails to provide basic public goods, resulting in low growth due to lack of order, security, and infrastructure.
  • An oversized government leads to inefficiencies, less incentive for private enterprise, and lower economic growth due to excessive regulation, high taxation, and crowding out.

Historical Context

The Armey curve is named after U.S. Representative Dick Armey, who popularized it in the 1990s. Its logic parallels the Laffer curve, but focuses on the broader scope of government spending rather than just tax rates.

Understanding Negative Growth Rate Values

In the mathematical model, government spending levels beyond the optimal point can produce negative growth rate values. While sustained negative growth (economic contraction) is possible in reality, these extreme negative values represent theoretical scenarios of economic dysfunction:

  • Economic stagnation: Excessive government spending (beyond the optimal point) creates such massive inefficiencies and crowding out of private investment that the economy contracts rather than grows.
  • Regulatory capture: Oversized government becomes dominated by special interests and rent-seeking behavior, leading to resource misallocation and economic decline.
  • Investment flight: Private businesses and entrepreneurs abandon the economy due to excessive bureaucracy, high taxes needed to fund large government, and lack of economic freedom.
  • Productivity collapse: Innovation, entrepreneurship, and productive economic activity become so constrained by government interference that overall economic output shrinks.

In practice, extremely negative growth rates would signal economic crisis and would likely trigger policy corrections before reaching the theoretical extremes suggested by the mathematical model.

Comparative Findings

  • Optimal government size can vary with factors like openness of the economy, population size, and national context.
  • Empirical studies find different threshold values for optimal government size in countries such as the U.S., France, Kenya, Turkey, and Georgia—ranging from less than 20% up to 30% of GDP.

In summary, the Armey curve highlights that both too little and too much government spending can harm economic growth, and seeks to identify the optimal share that maximizes prosperity.

Natural growth rate without government intervention
Initial positive effect of government spending
Diminishing returns effect (must be negative)
About the Laffer Curve

The Laffer curve illustrates the theoretical relationship between rates of taxation and the resulting levels of consent to taxation. It suggests that at a tax rate of 0%, consent is zero (no taxes means no need for consent), and at 100%, consent becomes -100% because there is no incentive to work or produce under complete confiscation. Between these extremes, consent rises to a maximum and then falls.

Curve Structure

The Laffer curve is depicted as an inverted U-shaped graph. The horizontal axis represents the tax rate (from 0% to 100%), and the vertical axis shows consent to taxation. The peak indicates the optimal tax rate that maximizes societal acceptance, beyond which higher rates reduce consent due to disincentives and resistance.

Important note on the y-axis: The y-axis doesn't measure literal revenue but rather the theoretical economic health and viability of the tax system. Thus, negative values serve as a warning of extreme disincentives and economic dysfunction rather than actual negative tax revenue.

Why Consent to Taxation Increases Initially

Consent to taxation rises from 0% to the optimal point for several interconnected reasons:

  • Social contract fulfillment: As tax rates increase from zero, governments can provide essential public goods (defense, law enforcement, infrastructure) that citizens value, creating legitimate reasons for taxation.
  • Economic productivity gains: Moderate taxation enables public investments that boost overall economic productivity, making the tax burden worthwhile as citizens see their living standards improve.
  • Perceived fairness: When tax rates are reasonable and well-spent, citizens view taxation as a fair contribution to collective welfare rather than confiscation.
  • Institutional trust: Effective government services funded by moderate taxes build public trust in institutions, increasing voluntary compliance and acceptance.
  • Collective benefit recognition: Citizens understand that moderate taxation enables shared benefits (education, healthcare, infrastructure) that would be impossible to achieve individually.

Beyond the optimal point, consent declines as the marginal costs of higher taxes (reduced incentives, economic inefficiency) outweigh the marginal benefits of additional government services.

Mathematical Formulation

The curve can be modeled with a quadratic equation:

R = β₀ + β₁ · t + β₂ · t²

where R is tax revenue, t is the tax rate, β₀ is often 0, β₁ > 0, and β₂ < 0 to create the parabolic shape. More advanced models may use different functional forms.

Policy Implications

  • If tax rates are below the peak, increasing them can boost revenue.
  • If rates are above the peak, cutting taxes can stimulate economic activity, leading to higher revenue over time.
  • It highlights the trade-off between tax rates and economic incentives, influencing debates on supply-side economics.

Historical Context

Popularized by economist Arthur Laffer in 1974 during a meeting with U.S. policymakers, the concept has roots in earlier thinkers like Ibn Khaldun (14th century) and John Maynard Keynes. It gained prominence in the 1980s under Reagan's tax cuts.

Understanding Negative Revenue Values

In the mathematical model, tax rates above 50% produce negative revenue values. While negative tax revenue is impossible in reality, these values represent theoretical economic collapse scenarios:

  • Economic collapse: Extremely high tax rates (above 50% in this model) create such massive disincentives that economic activity collapses to the point where the government would theoretically need to pay people to engage in economic activity.
  • Underground economy: People completely exit the formal, taxable economy and move to barter, black markets, or simply stop productive activity altogether.
  • Capital flight: Businesses and wealthy individuals leave the country entirely, taking their economic activity with them.
  • Disincentive effects: Work, investment, and entrepreneurship become so unprofitable that they essentially cease, creating a death spiral where the tax base evaporates.

In practice, governments would see revenue approach zero rather than go negative, as the economy would collapse or transform into an untaxable shadow economy.

Comparative Findings

  • The consent-maximizing rate is often estimated around 25% for a balanced budget maximizing long term growth.

In summary, the Laffer curve demonstrates that tax rates and revenue are not linearly related, emphasizing the need to find the optimal rate that maximizes government income without stifling economic growth.

Base taxation consent level
Initial positive effect of taxation
Diminishing returns effect (must be negative)
About the J-Curve

The J-Curve shows what happens to an economy after a major policy change, like when a country suddenly devalues its currency or implements drastic budget cuts. The name comes from the "J" shape of the curve: things get worse before they get better. First, the economy dips down (the bottom of the J), then gradually recovers and eventually improves beyond where it started (the upward hook of the J).

How It Works

Imagine the graph: time moves along the bottom (months or years), and economic health goes up and down on the side. When a big policy change happens, the economy starts at a normal level, immediately drops to a low point, then slowly climbs back up and eventually rises higher than before. This creates a shape that looks like the letter "J".

The Math Behind It

The curve follows this pattern:

Y(t) = Base + Slope · t - Depth · (1 - e^{-t / τ})

What this means in plain English:

  • Base: Where the economy started before the shock
  • Depth: How bad things get initially (the deeper the dip, the harder it hits)
  • τ (tau): How long the pain lasts (higher number = longer recovery time)
  • Slope: How fast the economy improves in the long run

Why Does It Get Worse First?

When a government makes a big change, the negative effects hit immediately while the positive effects take time to materialize:

  • Immediate price shocks: If a currency loses value, imports become more expensive right away, but it takes time for exports to increase (people still buy the same things out of habit).
  • Loss of confidence: People and businesses panic and cut back spending, making things worse temporarily.
  • Budget cuts hurt first: When government spending gets slashed, jobs are lost and services disappear before new private sector growth can replace them.

What This Means for Policy

  • Patience required: Governments must endure the difficult period to reach the recovery phase.
  • Support helps: Providing temporary assistance (like unemployment benefits or food aid) can make the dip less severe.
  • Warning sign: If the economy doesn't start recovering after the expected time, the policy might not be working (the J turns into an L - permanent decline).

Real-World Examples

Poland's "Shock Therapy" (1990-1992) - A Success Story

After communism fell in 1989, Poland implemented one of the first and most successful shock therapy programs under economist Leszek Balcerowicz. The country faced hyperinflation (600%), food shortages, and obsolete state-owned industries.

The Reforms (What They Did)
  • Price liberalization: Removed government price controls on nearly all goods
  • Currency reform: Made the zloty internally convertible and allowed market exchange rates
  • Budget discipline: Ended deficit financing by the central bank and controlled wage growth
  • Trade opening: Eliminated import restrictions and created uniform tariffs
The Dip (Things Got Worse)
  • GDP fell 9.78% in 1990 and 7.02% in 1991
  • Unemployment jumped from 0.3% to 6.5% in one year
  • Many inefficient state companies closed immediately
  • Widespread anxiety about economic future
The Recovery (Things Got Better)
  • Sustained growth: GDP grew steadily at 6-7% annually through the late 1990s and 2000s
  • Best in Europe: Poland's GDP increased 826.96% from 1989-2018, the highest growth in Europe
  • Only EU economy to avoid 2008 recession: Continued growing during the global financial crisis
  • Consumption of goods (cars, appliances, food) boomed as living standards rose
  • Upgraded to "developed market" status by FTSE Russell in 2018
Why Poland Succeeded

Unlike Russia's chaotic transition, Poland had several advantages: private agriculture still existed, democratic institutions were stable, privatization was more gradual and equitable, and the country maintained some social safety nets. This shows that shock therapy can work—but the details of implementation matter enormously.

Argentina's Economic Shock (2023-2025) - Ongoing

In late 2023, Argentina implemented radical economic changes, creating a textbook J-Curve scenario:

The Reforms (What Was Done)
  1. Currency devaluation: Let the peso drop in value from 400 to 800 per US dollar
  2. Budget cuts: Slashed government spending from over 5% deficit to achieve a surplus
  3. Deregulation: Removed many government controls on business and markets
The Dip (Things Got Worse)
  • Economy shrank: -1.6% in 2023, -3.5% in 2024
  • Inflation soared to 237% per year
  • Poverty jumped from 38% to 53% initially
  • Many people lost jobs and businesses struggled
The Recovery (Things Got Better)
  • Inflation dropped dramatically to under 3% per month
  • Poverty fell back to 38% by end of 2024
  • Economy projected to grow +5% in 2025
  • First budget surplus in 14 years (government income exceeds spending)
  • Argentina's credit rating improved
  • Currency stabilized with only 1% monthly devaluation
The Ongoing Challenge

By mid-2025, the recovery showed some fragility. The economy contracted again in Q2 2025, showing that J-Curves aren't always smooth. Global economic conditions and other factors can slow the recovery, reminding us that these reforms are risky and don't always work as planned.

Conditions for Success: Why Some Reforms Work and Others Fail

Comparing successful cases (like Poland) with failures (like Russia in the 1990s) reveals critical factors that determine whether a J-Curve leads to recovery or becomes an L-shaped permanent decline:

1. Pre-existing Market Infrastructure

What it means: Some functioning private sector, even if small (private farms, small businesses, market experience).

Why it matters: People need to know how markets work. Poland had private agriculture; Russia had complete state ownership. This gave Poles a head start in adapting to capitalism.

2. Stable Democratic Institutions

What it means: Legitimate government, rule of law, functioning courts, peaceful power transitions.

Why it matters: Without stability, reforms can't be properly implemented. Corruption flourishes, contracts aren't enforced, and public trust evaporates. Poland had stable democracy; Russia faced political chaos.

3. Gradual, Equitable Privatization

What it means: Careful transfer of state assets to private hands, avoiding concentration of wealth.

Why it matters: Rushed privatization (like Russia's voucher system) created oligarchs and extreme inequality. Poland's slower approach maintained public support and prevented wealth capture by a few insiders.

4. Social Safety Nets

What it means: Unemployment benefits, food assistance, healthcare, pension protection during transition.

Why it matters: Cushions the blow for those who lose jobs. Reduces human suffering, prevents social unrest, and maintains political support for continuing reforms. Poland kept safety nets; Russia largely didn't.

5. External Financial Support

What it means: Aid, loans, or investment from international institutions (IMF, World Bank, EU) or foreign investors.

Why it matters: Provides capital during the crisis, builds confidence, and helps stabilize currency. Poland had EU accession prospects; Argentina received $20B from the IMF.

6. Proper Sequencing

What it means: Doing reforms in the right order: price liberalization first, then privatization; monetary stability before structural reforms.

Why it matters: Wrong sequence amplifies chaos. If you privatize before establishing market prices, assets get sold at arbitrary values, enabling corruption and wealth theft.

7. Political Will and Public Patience

What it means: Government stays the course through 6-18 months of pain; population believes recovery will come.

Why it matters: If government caves to protests too early or reverses reforms, the pain was for nothing. Both Poland and Argentina maintained commitment despite protests.

8. Favorable Starting Conditions

What it means: Lower initial debt, younger population, intact trade relationships, moderate (not extreme) crisis.

Why it matters: Easier to recover from a shallow hole than a deep one. Countries with multiple compounding crises (debt + demographics + trade collapse) face much harder paths.

The Bottom Line on Success Factors

No single factor guarantees success, but countries with more of these advantages tend to achieve genuine J-Curves. Those lacking them (like Russia in the 1990s) often experience L-curves—a dip without recovery. Implementation details matter as much as the policies themselves.

Key Takeaways

  • Timing matters: The worst part usually lasts 6-18 months, but recovery can take years
  • Context matters: Countries that trade a lot with other nations (like Argentina) tend to see sharper J-Curves - deeper dips but faster recoveries
  • Not guaranteed: Just because you make painful reforms doesn't mean recovery is certain - the economy could stay depressed (an L-shape instead of a J-shape)

Understanding Negative Values on the Chart

When the curve dips below zero, it represents a genuine economic crisis: businesses closing, people losing jobs, money fleeing the country, and widespread hardship. These negative values show the real human cost of economic shocks before recovery begins.

Bottom line: The J-Curve teaches us that major economic reforms often cause significant pain before delivering benefits. It's like economic surgery - the recovery period is tough, but the goal is to emerge healthier than before.

Pre-shock economic indicator
Initial shock severity
Time constant for recovery (higher = slower)
Long-term improvement rate
About Supply and Demand

The supply and demand model is the cornerstone of economics, illustrating how buyers (demand) and sellers (supply) interact to determine price and quantity in a market. Demand slopes downward: as price falls, more is bought. Supply slopes upward: as price rises, more is sold. Their intersection yields equilibrium—the price where quantity demanded equals quantity supplied, and markets clear without surplus or shortage.

Historical Development of the Supply and Demand Diagram

The visual representation of supply and demand evolved over more than 50 years through the contributions of several pioneering economists:

  • 1838 - Augustin Cournot: The French mathematician and economist drew the first demand curve in his groundbreaking work "Recherches sur les Principes Mathématiques de la Théorie des Richesses" (Mathematical Principles of the Theory of Wealth). Cournot was the first to graphically represent the inverse relationship between price and quantity demanded.
  • 1870 - Fleeming Jenkin: The Scottish engineer and economist introduced the supply curve and created the first combined graphical representation in his paper "The Graphic Representation of the Laws of Supply and Demand." Jenkin showed how both curves could be plotted together to find equilibrium.
  • 1890 - Alfred Marshall: The British economist popularized the joint supply-and-demand diagram in his influential textbook "Principles of Economics." Marshall's clear exposition and pedagogical approach—now commonly called the "Marshallian cross"—cemented the supply-and-demand framework as central to economic analysis. His work made the diagram the standard tool it remains today.

Historical Timeline: 1838 (Cournot - demand curve) → 1870 (Jenkin - supply curve & combination) → 1890 (Marshall - popularization). This gradual development shows how economic tools evolve through the collaborative efforts of thinkers building on each other's insights.

Why Curved Lines? (Not Straight Lines)

This simulator uses curved supply and demand lines, which is more realistic than the straight lines often shown in textbooks. Here's why:

  • Demand curves down (convex to origin): The first unit of anything provides the most satisfaction. Your first cup of coffee in the morning is amazing, the second is good, the tenth makes you jittery. This "diminishing marginal utility" means price must drop more dramatically to get people to buy additional units. The curve starts steep (high value for first units) then flattens (low value for last units).
  • Supply curves up (convex from origin): The first units are cheap to produce using your best resources and most efficient methods. But as you scale up, you face "increasing marginal costs"—overtime pay, less productive equipment, higher input prices. The curve starts flat (easy to produce more initially) then steepens (expensive to keep expanding).

Straight lines are simpler for teaching basics, but curved lines better represent how real markets actually work. You'll see these curved shapes in actual economic data and professional analysis.

Spontaneous Order and the Market Discovery Process

The supply and demand model reveals one of economics' most profound insights: market prices and resource allocation emerge spontaneously through voluntary exchange, without central planning or coordination. This phenomenon, called "spontaneous order," demonstrates that complex economic coordination doesn't require a guiding authority—it arises naturally from individuals pursuing their own interests.

The Continuous Discovery Process

Markets are not static equilibrium points but rather dynamic discovery processes where entrepreneurs and consumers constantly adapt to changing conditions:

  • Entrepreneurs as discoverers: Business owners don't have perfect information—they make educated guesses about what consumers want, at what price, and how to produce it efficiently. Success means they discovered valuable knowledge about consumer preferences and production methods. Failure means the market signals them to try something else or exit. This trial-and-error process continually improves resource allocation without anyone consciously directing it.
  • Prices as information signals: Rising prices tell producers "make more of this, people want it!" while telling consumers "use less, it's scarce!" Falling prices signal the opposite. No central planner needs to coordinate millions of decisions—prices do it automatically by encoding vast amounts of dispersed knowledge into a single number everyone can see and act upon.
  • Consumer sovereignty: Consumers vote with their dollars, constantly expressing preferences through purchases. Entrepreneurs must serve these preferences to survive. Unlike political voting (which happens occasionally), market voting happens with every transaction, creating immediate, continuous feedback that guides production toward genuine human wants.
  • Adaptive competition: Multiple suppliers compete to serve consumers better, faster, or cheaper. This competition isn't wasteful—it's an evolutionary process that discovers better ways of doing things. When one entrepreneur innovates successfully, others imitate or improve, spreading knowledge throughout the economy without government mandates.

The Crucial Role of Non-Interference

This spontaneous order only functions when governments refrain from interfering with voluntary exchange. Price controls, production quotas, licensing restrictions, and other interventions short-circuit the discovery process:

  • Price ceilings block information: When government caps prices below market equilibrium, shortages emerge—but the real damage is deeper. The price signal that would have told producers "make more!" gets muted. Entrepreneurs can't discover if high prices reflect temporary scarcity (requiring more production) or changing preferences (requiring innovation) because the price is artificially frozen.
  • Price floors create waste: Minimum prices above equilibrium create surpluses—resources deployed to produce things nobody wants at that price. The market's feedback mechanism (falling prices signaling "produce less") is disabled, preventing the reallocation of resources to more valued uses.
  • Regulations freeze discovery: Licensing requirements, building codes, and occupational restrictions prevent entrepreneurs from experimenting with new business models, production methods, or service offerings. What looks like "protecting consumers" actually protects incumbent businesses from innovative competition, slowing the discovery of better ways to serve people.
  • Subsidies distort signals: When governments subsidize production (corn ethanol, solar panels, electric cars), prices no longer reflect true costs and consumer preferences. Resources flow to politically favored industries rather than where consumers actually want them, undermining the market's allocative efficiency.

The Humility Principle

The supply and demand model teaches epistemic humility: no individual, committee, or government possesses the knowledge scattered across millions of people to centrally plan an economy. Consumer preferences, production technologies, resource availabilities, and individual circumstances change constantly—far too fast and complex for any planning agency to track. The market doesn't require anyone to know everything; it only requires freedom for individuals to act on their local knowledge through voluntary exchange.

When left free to operate, supply and demand coordinates the actions of strangers who never meet, allocates resources to their highest-valued uses as judged by consumers, incentivizes innovation and efficiency, and creates prosperity—not because anyone designed it to do so, but because voluntary exchange naturally aligns individual incentives with social benefit. Government interference, however well-intentioned, disrupts this delicate coordination mechanism, creating shortages, surpluses, misallocations, and stifled innovation.

Curve Structure

The graph plots price (vertical axis) against quantity (horizontal axis). The demand curve descends from left to right; the supply curve ascends. Shifts in either curve (due to taxes, subsidies, preferences, or costs) alter equilibrium, revealing surpluses (excess supply) or shortages (excess demand).

Understanding Curve Shifts (Movement vs. Shift)

It's crucial to understand the difference between moving along a curve and shifting the entire curve:

Movement Along a Curve

This happens when the price changes but the curve itself stays in place. You're just moving to a different point on the same line. For example:

  • On the demand curve: If the price drops from $70 to $50, consumers buy more (move down and right along the curve)
  • On the supply curve: If the price rises from $70 to $90, producers supply more (move up and right along the curve)

Shifting the Entire Demand Curve

The entire demand curve shifts right or left when something OTHER than price changes consumer behavior:

  • Shift Right (Increase in Demand): At every price, consumers want MORE
    • Higher incomes (people have more money to spend)
    • Product becomes trendy/popular (fashion, viral marketing)
    • Price of substitutes rises (if beef gets expensive, demand for chicken shifts right)
    • Price of complements falls (if TVs get cheaper, demand for streaming subscriptions shifts right)
    • Expected future price increase (people buy now before prices rise)
    • Population increase (more buyers in the market)
    Mathematically: Increases the 'a' parameter (demand intercept)
  • Shift Left (Decrease in Demand): At every price, consumers want LESS
    • Lower incomes (recession, job losses)
    • Product goes out of fashion
    • Health concerns (demand for cigarettes shifted left after health warnings)
    • Price of substitutes falls (cheap alternatives emerge)
    Mathematically: Decreases the 'a' parameter (demand intercept)

Shifting the Entire Supply Curve

The entire supply curve shifts right or left when something OTHER than price changes producer behavior:

  • Shift Right (Increase in Supply): At every price, producers supply MORE
    • Technology improves (automation, better machines make production cheaper)
    • Input costs fall (raw materials, labor, energy get cheaper)
    • Government subsidies (producers get paid to produce)
    • Good weather (for agriculture)
    • More producers enter the market
    • Expected future price decrease (sell now before prices drop)
    Mathematically: Decreases the 'c' parameter (supply intercept - lower minimum price needed)
  • Shift Left (Decrease in Supply): At every price, producers supply LESS
    • Input costs rise (oil shock raises energy costs)
    • Government regulations increase costs
    • Natural disasters (hurricanes, droughts)
    • Producers exit the market
    • Taxes on production
    Mathematically: Increases the 'c' parameter (supply intercept - higher minimum price needed)

Impact on Equilibrium

  • Demand shifts right: Equilibrium price ↑, equilibrium quantity ↑
  • Demand shifts left: Equilibrium price ↓, equilibrium quantity ↓
  • Supply shifts right: Equilibrium price ↓, equilibrium quantity ↑
  • Supply shifts left: Equilibrium price ↑, equilibrium quantity ↓

How to Simulate Shifts with This Tool

You can simulate these shifts by adjusting the parameters:

  • To shift demand right (increase): Increase the 'a' parameter (e.g., from 120 to 140)
  • To shift demand left (decrease): Decrease the 'a' parameter (e.g., from 120 to 100)
  • To shift supply right (increase): Decrease the 'c' parameter (e.g., from 20 to 10)
  • To shift supply left (decrease): Increase the 'c' parameter (e.g., from 20 to 30)

Try it: Change 'a' from 120 to 140 and click Simulate. You'll see the demand curve shift right, creating a higher equilibrium price and quantity!

Mathematical Formulation

Curved Demand (Realistic Model): P = a / (1 + bQ)^0.5
This creates a convex curve showing diminishing marginal utility—each additional unit provides less value to consumers.

Curved Supply (Realistic Model): P = c + d·Q^1.3
This creates a convex curve showing increasing marginal costs—each additional unit becomes more expensive to produce.

Equilibrium: Found where demand price equals supply price (solved numerically)

Why Decimal Quantities? (Understanding Continuous Models)

You might notice the equilibrium shows decimal quantities like "55.75 units" instead of whole numbers. This isn't a mistake—it's how economic models work in practice:

  • Aggregate Market Scale: The curves represent entire markets, not individual purchases. "55.75 units" might mean 55.75 million smartphones per quarter, 55.75 thousand cars per month, or 55.75 tons of steel. The decimal represents a large-scale aggregate across all buyers and sellers in the market.
  • Continuous Production: Many goods are naturally measured in decimals— 55.75 barrels of oil, 55.75 gallons of milk, 55.75 kilowatt-hours of electricity, 55.75 cubic meters of lumber, or 55.75 hours of labor services. These aren't discrete individual items but continuous quantities.
  • Time-Based Rates: Quantities often represent rates over time periods. For example, "55.75 units" could mean an average production/consumption rate: a factory might produce 55 units one day and 56 the next, averaging 55.75 over the period.
  • Mathematical Smoothness: Real markets involve millions of transactions by countless buyers and sellers. Treating quantity as a continuous variable (using calculus and smooth curves) provides a much simpler and more elegant model than trying to track each discrete transaction. The curves are smooth approximations that capture aggregate behavior.
  • Professional Standard: In academic economics, government analysis, and business forecasting, decimal quantities are the norm. Economists routinely work with values like "GDP grew by 2.3%" or "unemployment is 4.7%"—precision matters for policy and investment decisions.

Bottom line: While buying 0.75 of an individual apple doesn't make sense, an economy producing or consuming 55.75 million apples per year, or a market clearing at 55.75 tons of apples, is perfectly reasonable. The model represents aggregate market behavior, not individual purchases.

Understanding the Parameters (For Beginners)

Demand Parameters

a - Demand Scale Factor:

This controls the overall level of the demand curve—how high it sits on the price axis. A higher 'a' means consumers are willing to pay more at any given quantity. Think of it as the "value intensity"—how much consumers value this product. For luxury goods or essentials, this would be high. For low-value items, it would be low. For example, if a = 120, consumers place high value on the product and are willing to pay premium prices.

b - Demand Curvature (Diminishing Utility Rate):

This controls how quickly consumer willingness to pay decreases as they buy more. A higher 'b' means the curve drops faster—each additional unit loses value more rapidly (strong diminishing marginal utility). A lower 'b' means consumers maintain their willingness to pay longer as quantity increases. For example, if b = 2, consumer valuations drop moderately with each additional purchase. Think: the first ice cream is worth $5, the second $3, the third $1.

Supply Parameters

c - Minimum Production Cost (Supply Base):

This is the base cost of production—the minimum price producers need even for small quantities. It represents fixed costs and baseline variable costs. If the market price falls below this, producers won't supply anything because they'd lose money on every unit. For example, if c = 20, producers need at least $20 per unit to cover their basic costs of materials, labor, and overhead.

d - Marginal Cost Growth Rate:

This controls how rapidly production costs accelerate as output increases. A higher 'd' means costs rise very quickly with more production (steep curve)—you quickly hit capacity constraints, need expensive overtime, less efficient equipment, etc. A lower 'd' means costs rise more gradually. For example, if d = 2, costs accelerate moderately. The curve shape (Q^1.3) means producing the 100th unit costs much more than the 10th unit—capturing the reality of diminishing returns and capacity constraints.

How These Work Together (Curved Model)

The realistic curved model captures key economic realities that linear models miss:

  • Demand curves down more steeply at first then flatten—the first few units have high value, but eventually everyone who really wants the product has bought it, leaving only marginal buyers.
  • Supply curves up more gradually at first then steepen—initial production uses the best resources and most efficient methods, but expanding requires increasingly costly approaches (overtime, new facilities, less productive workers).
  • Equilibrium emerges naturally where these curved forces balance—where the marginal consumer's willingness to pay exactly matches the marginal producer's cost.

This curved model is more realistic than straight lines because it reflects how people actually behave: diminishing marginal utility for consumers and increasing marginal costs for producers.

Understanding Negative Prices

In the mathematical model, you may see negative prices on the chart at very high quantities. While negative prices are unusual in real markets, they can occur in special circumstances and help illustrate important economic concepts:

On the Demand Curve (Negative Willingness to Pay)

When the demand curve drops below zero, it means consumers would need to be paid to take the product. Real-world examples include:

  • Waste disposal: If you produce too many widgets that nobody wants, you might have to pay people to haul them away
  • Negative oil prices (2020): During COVID-19, oil storage filled up and producers literally paid buyers to take oil off their hands rather than shut down wells
  • Perishable goods: A restaurant with too much food at closing time might give it away free or even pay to have it removed
  • Excess inventory: Companies sometimes pay liquidators to clear out unsold merchandise

On the Supply Curve (Negative Production Costs)

When the supply curve goes below zero at low quantities, it represents a theoretical scenario where producers would pay to produce. While rare, this can happen when:

  • Byproduct value: Manufacturing a product generates valuable byproducts that offset costs (though this usually adjusts the cost structure)
  • Government subsidies: Producers receive payments that exceed their production costs
  • Learning by doing: Early production builds skills and knowledge worth more than the cost

Practical Note

In most real markets, producers simply stop supplying when prices fall too low, and consumers stop demanding at very high prices. Negative prices represent extreme theoretical scenarios that help us understand the mathematical model. For educational purposes, they demonstrate that these are linear projections—in reality, markets don't operate at these extreme quantities.

Policy Implications

  • Price ceilings create shortages; floors, surpluses.
  • Taxes shift supply up, reducing quantity; subsidies shift down, increasing it.
  • Elasticity (b, d) shows responsiveness: This measures how much quantity changes when price changes.
    • Steep curves (high b or d values) = Inelastic/Rigid markets: Quantity doesn't change much even with big price changes. Examples: insulin (people need it regardless of price), gasoline in the short term (you still need to drive to work), salt (you use about the same amount no matter the price). The curve is steep/vertical because quantity is relatively fixed.
    • Flat curves (low b or d values) = Elastic/Flexible markets: Quantity changes a lot with small price changes. Examples: restaurant meals (if one place raises prices, people easily switch to competitors), luxury goods (if designer bags get too expensive, people skip them), seasonal fruits (if strawberries are expensive, buy blueberries instead). The curve is flat/horizontal because consumers or producers react strongly to price.
    • Why this matters for policy: Taxing inelastic goods (like cigarettes or gasoline) raises lots of revenue because people keep buying. Taxing elastic goods raises less revenue because people quickly switch to alternatives. Similarly, subsidizing inelastic goods doesn't boost consumption much, but subsidizing elastic goods can dramatically increase purchases.

Historical Context

Rooted in Adam Smith's "invisible hand" (1776), formalized by Alfred Marshall in 1890. It underpins modern microeconomics, guiding antitrust, trade, and regulation.

In summary, supply and demand reveals the invisible forces that balance markets—or disrupt them under princely decree.

Overall demand level - how much consumers value the product
How fast marginal utility diminishes
Baseline production cost
How fast costs accelerate with production
About the Division of Labor & Market Size Curve

The Division of Labor & Market Size curve, based on Adam Smith's famous "Pin Factory" example, demonstrates one of the most powerful insights in economics: the division of labor—limited by the extent of the market—is the primary engine of productivity growth and prosperity.

The Pin Factory: Adam Smith's Revolutionary Insight

In The Wealth of Nations (1776), Adam Smith observed that a single worker making pins alone could produce perhaps 20 pins per day. But when the process was divided into 18 specialized tasks shared among 10 workers, each worker could produce an astonishing 4,800 pins per day—a 240-fold increase in productivity! This wasn't just efficiency; it was a complete transformation of economic output.

Key Economic Principles

This model demonstrates the fundamental importance of increasing returns to scale—the true driver of the 100-fold increase in per capita GDP over the last 250 years. Key insights include:

  • Increasing returns, not diminishing returns: As markets grow and specialization deepens, productivity increases exponentially—not marginally. This is the "pin factory" vs. the neoclassical trap.
  • Market size enables specialization: Smith wrote: "the division of labor is limited by the extent of the market." Larger markets allow more specialized workers, leading to dramatic productivity gains.
  • Free trade expands prosperity: By expanding market size beyond national borders, free trade enables even greater specialization and wealth creation.
  • Social cooperation through voluntary exchange: The division of labor requires peaceful cooperation. As Frédéric Bastiat said: "Where commerce enters, bullets do not."
  • Entrepreneurship and spontaneous order: No central planner designs the division of labor—it emerges spontaneously through the market process and the "invisible hand."

The Mathematics of Increasing Returns

The model shows productivity as a function of specialization enabled by market size:

Productivity = Base × (1 + Workers × Specialization Factor)Returns Parameter

Where:

  • Base productivity: Output per worker in isolation (e.g., 20 pins/day)
  • Workers: Number of workers (representing market size/population)
  • Specialization factor: How much specialization each additional worker enables
  • Returns parameter: Degree of increasing returns (>1 means increasing returns to scale)

Why This Matters for Policy

Free Markets Enable Specialization

Government intervention—through regulation, trade barriers, taxes, and restrictions—limits market size and prevents specialization. This destroys the very mechanism that creates prosperity. Excessive regulations can be a primary cause of economic decline.

Private Property is Essential

The division of labor requires secure private property rights and voluntary exchange. Without property rights, there's no basis for specialized production and trade. This is why socialism—which attacks private property—inevitably leads to poverty.

Population Growth is Good

Contrary to Malthusian pessimism, more people mean larger markets, more specialization, and higher productivity for everyone. The world population multiplied 7x from 1810 to 2000, yet per capita output grew 9.2x—productivity grew faster than population!

Trade Barriers Destroy Wealth

Protectionism artificially limits market size, forcing people back toward self-sufficiency (like the solitary pin-maker producing only 20 pins). Free trade expands markets and enables the specialization that creates wealth.

Historical Evidence

From year 0 to 1800, per capita GDP grew only 48% (0.02% annually) under conditions of limited trade and small markets. From 1800 to 2000, with expanding free trade and market integration, per capita GDP grew 820% (multiplied by 9.2x). The difference? Increasing returns from expanding division of labor in larger markets.

Interactive Controls

Adjust the parameters below to see how market size, specialization depth, and the degree of increasing returns affect productivity. Notice how small increases in market size (enabling more workers/specialization) create exponential productivity gains—not linear ones. This is Adam Smith's insight and the foundation of modern prosperity.

Parameter Explanations

  • Base Productivity: Output when a worker produces alone (Smith's example: 20 pins/day)
  • Maximum Workers (Market Size): Number of workers that can specialize (represents market size)
  • Specialization Factor: How much each additional specialized worker boosts productivity (calibrated to Smith's 240× gain)
  • Returns to Scale Parameter: Degree of increasing returns (1.5 = strong increasing returns matching Smith's observations)
About Hockey Stick: Capitalism's Prosperity Explosion

"The Hockey Stick" demonstrates the most dramatic economic transformation in human history, showing a stunning visual pattern: for 1,800 years, per capita GDP barely moved—then suddenly exploded after 1800 when capitalism emerged.

The Most Important Graph in Economics

When you plot per capita GDP from year 0 to present, the curve looks exactly like a hockey stick: flat for millennia (the handle), then shooting upward exponentially (the blade). This isn't a gradual improvement—it's a complete rupture with all prior human history.

Historical Economic Data

Here are the precise numbers that demonstrate capitalism's transformative impact:

  • Year 0 - 1800 (1,800 years): Per capita GDP rose only 48% over eighteen centuries—a compound annual growth rate of just 0.02%. At that pace, it would take 3,500 years to double living standards!
  • 1800-1900 (Industrial Revolution): Growth rate jumped to 0.66% annually. Doubling time: 107 years.
  • 1900-1950: Growth accelerated to 1.66% annually. Doubling time: 66 years.
  • 1950-2000: Growth rate reached 2.1% annually. Doubling time: 33 years.
  • 2000-2025: Growth hit 3.0% annually. Doubling time: only 23 years!

Bottom line: From 1800 to present, per capita GDP multiplied by more than 15 times globally. This happened in just 200 years after 1,800 years of near-total stagnation. The growth rate is still accelerating!

The Poverty Miracle

The Hockey Stick isn't just about wealth—it's about lifting humanity from misery:

  • 1810: 95% of humanity lived in extreme poverty (less than $1/day equivalent)
  • 1900: Still around 90%
  • 2000: Down to 15%
  • 2020 (pre-pandemic): Only 5% in extreme poverty

"Capitalism lifted 90% of the world's population out of extreme poverty—and continues to do so at an accelerating pace."

Why The Hockey Stick Matters

This curve illustrates that the explosion occurred precisely when humanity adopted:

  1. Private property rights (secure ownership enabling long-term investment)
  2. Free markets (voluntary exchange without state coercion)
  3. Limited government (rule of law, not rule of bureaucrats)
  4. Division of labor (enabled by market expansion and free trade)
  5. Economic freedom (entrepreneurs free to innovate and compete)

The timing is too perfect to be coincidence. For 1,800 years under feudalism, monarchy, and central planning, humanity was trapped in poverty. Then came Adam Smith's Wealth of Nations (1776), the American Revolution (1776), and the unleashing of market forces—and suddenly the hockey stick begins.

The Interactive Model

This simulator lets you explore different scenarios by adjusting the "capitalism adoption year." See what happens if capitalism had emerged earlier—or later. The model uses actual historical data to show:

  • Before capitalism: Flat growth (0.02% annual) - the handle
  • After capitalism: Exponential acceleration - the blade

A Challenge to Critics

"How can anyone demonize an economic system that not only lifted 90% of the world's population out of extreme poverty, but continues to drive unprecedented prosperity? There has never been, in all of human history, a time of greater prosperity than the one we live in today."

The Hockey Stick is visual proof that capitalism isn't just efficient—it's one of the greatest humanitarian achievements in human history.

The simulator uses a piecewise function matching historical phases. In the two centuries since capitalism's adoption (typically 1800), per capita GDP has multiplied by approximately 15-40× depending on the region, lifting billions out of poverty. Today's world average is around $25,000 PPP per capita (2023 IMF data), up from ~$600-700 in year 0 / ~$650 in 1800.

GDP(year) = { Pre-Capitalism: Base × (1.0002)(year - 0) }
{ Post-Capitalism: Accelerating Exponential Growth }

Where growth rates shift through five distinct historical phases.

Key Insights

  • The flat handle represents all of pre-capitalist human history—empires, kingdoms, feudalism, mercantilism
  • The explosive blade begins exactly when free markets and property rights emerged
  • Growth is accelerating, not slowing—contrary to neo-Malthusian doomsayers
  • Population grew 7× from 1810-2000, yet per capita GDP grew 9.2× (total GDP: 63×!)
  • This demolishes the neoclassical assumption of diminishing returns—we see increasing returns

The Austrian Perspective

Unlike neoclassical models that struggle to explain the Hockey Stick (Solow-Swan only accounts for 15% of growth via capital accumulation), the Austrian approach emphasizes:

  • Entrepreneurial discovery as the driver of innovation
  • Knowledge accumulation and human action, not just capital and labor
  • Institutional quality—secure property rights create incentives for wealth creation
  • Spontaneous order—no central planner designed this prosperity

Why It's Called "The Hockey Stick"

The name comes from the unmistakable shape: lay a hockey stick on its side, and that's what history looks like. This term is widely used because it's the most intuitive way to grasp the magnitude of capitalism's transformative achievement.