The model library

65 of 103 models across 10 fields open a live, verified interactive graph. The rest are on the roadmap, built fastest where you hit “notify me”.

Production Possibility FrontierScarcity, tradeoffs, and opportunity cost on one curve, what an economy can produce and what growth looks like.InteractiveIntro Absolute vs. Comparative AdvantageWhy parties gain from trade even when one is better at everything, opportunity cost does the work.InteractiveIntro Supply & DemandThe workhorse of economics: how buyers and sellers set price and quantity in a single market.InteractiveIntro Price Elasticity of Demand & SupplyHow strongly quantity responds to price, and why it decides who bears taxes and how revenue moves.InteractiveIntro Income & Cross-Price ElasticityNormal vs. inferior goods, substitutes vs. complements, explored through demand shifts in the elasticity model.InteractiveIntro Consumer & Producer SurplusThe gains from trade made visible: willingness to pay above price, and price above cost.InteractiveIntro Price Ceilings & FloorsRent control and minimum prices: what happens when the law blocks the market from clearing.InteractiveIntro Taxes & Subsidies (Incidence, DWL)Who really pays a tax, who pockets a subsidy, and the deadweight loss triangle in between.InteractiveIntro Cost Curves & the MR = MC RuleMC, AC and the profit-maximizing rule every firm follows, rendered live inside the monopoly model.InteractiveIntro MonopolyOne seller, downward MR, and a markup over marginal cost, with the profit rectangle shaded live.InteractiveIntro Perfect CompetitionPrice-taking firms, zero long-run profit, and why entry and exit discipline the market.InteractiveIntro Oligopoly & Monopolistic CompetitionThe realistic middle ground: few sellers, differentiated products, and strategic pricing.InteractiveIntermediate Externalities & Pigouvian TaxesWhen markets ignore third parties, pollution, vaccines, and the tax/subsidy that fixes the price.InteractiveIntro Public Goods & the Free-Rider ProblemNon-rival, non-excludable goods that markets under-provide, from lighthouses to national defense.InteractiveIntro Tragedy of the CommonsShared resources, individual incentives, collective ruin, and the property-rights fix.InteractiveIntro Circular Flow of IncomeHouseholds, firms, government, and the rest of the world, with leakages and injections mapped.Coming soonIntro

Consumer Theory (Indifference Curves)Preferences meet the budget constraint: utility maximization and where demand curves come from.InteractiveIntermediate Slutsky Equation & Hicksian DemandDecomposing a price change into substitution and income effects. Marshallian vs. compensated demand.Coming soonAdvanced Producer Theory (Isoquants & Isocosts)The firm's version of consumer theory: input mixes, returns to scale, and cost-minimizing bundles.InteractiveIntermediate Cost Minimization & Profit MaximizationThe Lagrangian setup behind firm behavior, first-order conditions with economic meaning.Coming soonAdvanced General Equilibrium & the Edgeworth BoxAll markets clearing at once: the contract curve, Walras' law, and gains from exchange.Coming soonAdvanced Welfare Economics & Pareto EfficiencyWhen is an allocation efficient, when is it fair, and why the two welfare theorems matter.Coming soonIntermediate Game Theory & Nash EquilibriumStrategic interaction: dominant strategies, the Prisoner's Dilemma, and best responses.Coming soonIntermediate Cournot CompetitionOligopolists choosing quantities: reaction functions and an equilibrium between monopoly and competition.InteractiveAdvanced Bertrand & Stackelberg CompetitionPrice competition's brutal logic and first-mover advantage, contrasted against Cournot in the reaction-function model.InteractiveAdvanced Repeated Games & the Folk TheoremHow cooperation survives among the self-interested when the game never ends.Coming soonAdvanced Bayesian Games & Incomplete InformationStrategy when you don't know who you're playing against, types, beliefs, and Bayesian equilibrium.Coming soonAdvanced Adverse Selection (Lemons Problem)Akerlof's used-car market: how hidden quality can unravel a market entirely.InteractiveAdvanced Moral HazardHidden actions after the contract is signed, insurance, effort, and incentive design.Coming soonAdvanced Signaling & Screening (Spence)Costly signals that separate types, why education can pay even if it teaches nothing.Coming soonAdvanced Auction TheoryFirst-price, Vickrey, and common-value auctions, bidding strategy and the winner's curse.InteractiveAdvanced

AS-AD (Aggregate Supply – Aggregate Demand)The flagship macro diagram: demand shocks, supply shocks, and the short-run vs. long-run distinction.InteractiveIntro Keynesian Cross & the MultiplierPlanned spending meets the 45° line, watch a $1 injection multiply into more output.InteractiveIntro Phillips CurveThe inflation-unemployment tradeoff, real in the short run, gone in the long run.InteractiveIntro GDP, Unemployment & Inflation MeasurementHow the headline numbers are actually built: expenditure and income approaches, CPI, labor force stats.Coming soonIntro Business Cycle PhasesBoom, peak, recession, trough, the anatomy of fluctuations around trend growth.InteractiveIntro Money MultiplierHow fractional-reserve banking turns base money into broad money, and the leaks in the process.InteractiveIntro Quantity Theory of Money (MV = PY)The oldest idea in macro: money growth and inflation in the long run.InteractiveIntro Lorenz Curve & Gini CoefficientIncome inequality made visible: how far the income distribution sags from perfect equality, and the single number that summarises it.InteractiveIntro Laffer CurveThe tax-revenue hill: why revenue rises, peaks, then falls as tax rates climb, and why the peak location is the whole debate.InteractiveIntermediate

IS-LMGoods market meets money market: fiscal and monetary policy in one diagram.InteractiveIntermediate IS Curve Microfoundations (PIH)Deriving the IS curve properly, including what the Permanent Income Hypothesis does to fiscal policy.Coming soonAdvanced LM Curve / Money Market EquilibriumThe money-market foundations behind the LM curve, explore it live in the Money Market model.InteractiveIntermediate Mundell-Fleming (Open-Economy IS-LM)IS-LM with exchange rates: why policy works completely differently under fixed vs. floating regimes.InteractiveAdvanced Fisher EquationNominal rates, real rates, and expected inflation, the identity underneath monetary policy.InteractiveIntermediate Government Budget Constraint & SeigniorageDeficits, debt dynamics, and the inflation tax when governments print to pay.InteractiveAdvanced Solow-Swan Growth ModelCapital accumulation, diminishing returns, and the steady state, why saving alone can't drive growth forever.InteractiveIntermediate Harrod-Domar Growth ModelThe knife-edge predecessor to Solow: growth from the saving rate and capital-output ratio.InteractiveAdvanced Endogenous Growth (Romer, AK, Lucas)Growth from ideas and human capital, models where the growth rate itself is a choice.InteractiveAdvanced Ramsey-Cass-Koopmans ModelSolow with optimizing households: the saving rate chosen by intertemporal utility maximization.Coming soonAdvanced Overlapping Generations ModelYoung savers, old dissavers, a workhorse for pensions, bubbles, and dynamic inefficiency.Coming soonAdvanced Growth Accounting & the Solow ResidualDecomposing growth into capital, labor, and TFP, the measurement behind the theory.Coming soonAdvanced Malthusian Growth ModelWhy living standards were flat for millennia: population growth eating every productivity gain.InteractiveIntermediate Convergence HypothesisDo poor countries catch up? Absolute vs. conditional convergence and what the data says.InteractiveAdvanced New Keynesian 3-Equation ModelThe modern central-banking workhorse, its IS block, Phillips curve, and Taylor rule are each interactive here.InteractiveAdvanced Taylor RuleThe interest-rate rule that describes (and prescribes) how central banks respond to inflation and gaps.InteractiveIntermediate Real Business Cycle TheoryBusiness cycles as efficient responses to technology shocks, the provocation that built modern macro.Coming soonAdvanced Expectations-Augmented Phillips Curve / NAIRUWhy the tradeoff vanishes when expectations catch up, built live into our Phillips Curve model.InteractiveIntermediate

Labor Supply & DemandWage determination in a competitive labor market, productivity, participation, and equilibrium employment.InteractiveIntro Labor-Leisure TradeoffWork as a consumer choice: utility maximization with a time constraint, and backward-bending supply.InteractiveIntermediate Human Capital & the Mincer EquationEducation as investment: how schooling and experience price into earnings.InteractiveIntermediate Efficiency Wage TheoryWhy firms pay above market, morale, effort, and unemployment as a discipline device.Coming soonIntermediate Search & Matching (DMP)Unemployment as a matching problem: vacancies, job-finding rates, and the Beveridge curve.InteractiveAdvanced Bathtub Model of UnemploymentInflows and outflows setting the unemployment rate, the simplest honest model of the labor market.InteractiveIntermediate Monopsony & Minimum Wage ModelsWhen the employer has wage-setting power, a minimum wage can raise employment, the competitive vs. monopsony debate.InteractiveAdvanced

Ricardian Trade ModelComparative advantage formalized: technology differences, specialization, and the terms of trade.Coming soonIntermediate Heckscher-Ohlin ModelTrade driven by factor endowments, capital-rich countries export capital-intensive goods.Coming soonAdvanced Stolper-Samuelson TheoremTrade's distributional bite: who wins and who loses inside a country when it opens up.Coming soonAdvanced Gravity Model of TradeTrade flows predicted by size and distance, the most empirically successful model in economics.InteractiveIntermediate Purchasing Power ParityThe law of one price across borders. Big Mac index logic and long-run exchange rates.InteractiveIntermediate Balance of PaymentsCurrent account, capital account, and why the books always balance.Coming soonIntermediate Interest Rate ParityCovered and uncovered parity: how interest differentials pin down forward exchange rates.InteractiveAdvanced Tariffs & ProtectionThe protection diagram every syllabus draws: world price, tariff wedge, shrinking imports, and the deadweight triangles.InteractiveIntro J-CurveWhy a weaker currency makes the trade balance worse before it gets better, and what decides how long the dip lasts.InteractiveIntermediate

Money MarketMoney supply meets money demand, how the nominal interest rate is set.InteractiveIntro Loanable Funds MarketSaving supplies funds, investment demands them, the real interest rate clears the market.InteractiveIntro Baumol-Tobin Money DemandCash management as an inventory problem, the square-root rule for money holdings.InteractiveAdvanced Capital Asset Pricing Model (CAPM)Risk priced by beta: the security market line and the cost of equity.InteractiveIntermediate Efficient Market HypothesisPrices as information processors, weak, semi-strong, and strong forms, and the anomalies.Coming soonIntermediate Modigliani-Miller TheoremWhy capital structure is irrelevant in frictionless markets, and what the frictions change.Coming soonAdvanced Term Structure of Interest RatesWhat the yield curve knows: expectations, term premia, and inversion as recession signal.InteractiveAdvanced Black-Scholes Option PricingNo-arbitrage pricing of options, the formula that built modern derivatives markets.Coming soonAdvanced

Linear Regression & OLSSimple and multiple regression: fitting lines, reading coefficients, and R².InteractiveIntermediate Classical Assumptions (Gauss-Markov, BLUE)When OLS is the best you can do, and what breaks when each assumption fails.Coming soonIntermediate Instrumental Variables & 2SLSCausality from clever variation: instruments, relevance, exogeneity, and two-stage least squares.Coming soonAdvanced Hausman TestTesting for endogeneity and choosing between estimators. FE vs. RE, OLS vs. IV.Coming soonAdvanced Difference-in-DifferencesPolicy evaluation with a treated and control group, parallel trends and the 2×2 table.InteractiveAdvanced Panel Data (Fixed & Random Effects)Following units over time: sweeping out fixed characteristics to get closer to causality.Coming soonAdvanced Regression Discontinuity DesignCausal effects from cutoffs, comparing people just above and just below a threshold.Coming soonAdvanced Time Series (Unit Roots, Autocorrelation)Dickey-Fuller tests, spurious regression, HAC errors, the hazards of data over time.Coming soonAdvanced Trend vs. Difference StationarityWhether shocks die out or last forever, and why it changes how you model growth.Coming soonAdvanced Probit & Logit ModelsModeling yes/no outcomes: latent variables, marginal effects, and odds ratios.InteractiveAdvanced

Prospect TheoryKahneman & Tversky's value function: reference points, diminishing sensitivity, and risk attitudes that flip.InteractiveIntermediate Bounded RationalitySatisficing over optimizing, decision-making with limited attention, information, and computation.Coming soonIntermediate Hyperbolic Discounting & Present BiasWhy we plan patiently and act impulsively, beta-delta preferences and commitment devices.InteractiveIntermediate Nudge Theory & Choice ArchitectureDefaults, framing, and salience: steering choices without restricting them.Coming soonIntro Loss Aversion & the Endowment EffectLosses hurt about twice as much as gains feel good, see the kink live in the prospect theory value function.InteractiveIntro

Lagrangian MultipliersConstrained optimization's workhorse, and why the multiplier is a shadow price.Coming soonAdvanced Kuhn-Tucker (KKT) ConditionsOptimization with inequality constraints: complementary slackness and corner solutions.Coming soonAdvanced Envelope TheoremComparative statics via value functions, the shortcut behind Shephard's and Hotelling's lemmas.Coming soonAdvanced Hessian & Bordered HessianSecond-order conditions: checking that your optimum is actually a maximum.Coming soonAdvanced Comparative StaticsHow equilibria move when parameters change, practice it live in any interactive model, starting with Supply & Demand.InteractiveIntermediate Dynamic Optimization BasicsChoosing over time: Bellman thinking, Euler equations, and the tools behind Ramsey and RBC.Coming soonAdvanced