The model library
61 of 99 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.InteractiveIntroAbsolute vs. Comparative AdvantageWhy parties gain from trade even when one is better at everything, opportunity cost does the work.InteractiveIntroSupply & DemandThe workhorse of economics: how buyers and sellers set price and quantity in a single market.InteractiveIntroPrice Elasticity of Demand & SupplyHow strongly quantity responds to price, and why it decides who bears taxes and how revenue moves.InteractiveIntroIncome & Cross-Price ElasticityNormal vs. inferior goods, substitutes vs. complements, explored through demand shifts in the elasticity model.InteractiveIntroConsumer & Producer SurplusThe gains from trade made visible: willingness to pay above price, and price above cost.InteractiveIntroPrice Ceilings & FloorsRent control and minimum prices: what happens when the law blocks the market from clearing.InteractiveIntroTaxes & Subsidies (Incidence, DWL)Who really pays a tax, who pockets a subsidy, and the deadweight loss triangle in between.InteractiveIntroCost Curves & the MR = MC RuleMC, AC and the profit-maximizing rule every firm follows, rendered live inside the monopoly model.InteractiveIntroMonopolyOne seller, downward MR, and a markup over marginal cost, with the profit rectangle shaded live.InteractiveIntroPerfect CompetitionPrice-taking firms, zero long-run profit, and why entry and exit discipline the market.InteractiveIntroOligopoly & Monopolistic CompetitionThe realistic middle ground: few sellers, differentiated products, and strategic pricing.InteractiveIntermediateExternalities & Pigouvian TaxesWhen markets ignore third parties, pollution, vaccines, and the tax/subsidy that fixes the price.InteractiveIntroPublic Goods & the Free-Rider ProblemNon-rival, non-excludable goods that markets under-provide, from lighthouses to national defense.InteractiveIntroTragedy of the CommonsShared resources, individual incentives, collective ruin, and the property-rights fix.InteractiveIntroCircular 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.InteractiveIntermediateSlutsky Equation & Hicksian DemandDecomposing a price change into substitution and income effects. Marshallian vs. compensated demand.Coming soonAdvancedProducer Theory (Isoquants & Isocosts)The firm's version of consumer theory: input mixes, returns to scale, and cost-minimizing bundles.InteractiveIntermediateCost Minimization & Profit MaximizationThe Lagrangian setup behind firm behavior, first-order conditions with economic meaning.Coming soonAdvancedGeneral Equilibrium & the Edgeworth BoxAll markets clearing at once: the contract curve, Walras' law, and gains from exchange.Coming soonAdvancedWelfare Economics & Pareto EfficiencyWhen is an allocation efficient, when is it fair, and why the two welfare theorems matter.Coming soonIntermediateGame Theory & Nash EquilibriumStrategic interaction: dominant strategies, the Prisoner's Dilemma, and best responses.Coming soonIntermediateCournot CompetitionOligopolists choosing quantities: reaction functions and an equilibrium between monopoly and competition.InteractiveAdvancedBertrand & Stackelberg CompetitionPrice competition's brutal logic and first-mover advantage, contrasted against Cournot in the reaction-function model.InteractiveAdvancedRepeated Games & the Folk TheoremHow cooperation survives among the self-interested when the game never ends.Coming soonAdvancedBayesian Games & Incomplete InformationStrategy when you don't know who you're playing against, types, beliefs, and Bayesian equilibrium.Coming soonAdvancedAdverse Selection (Lemons Problem)Akerlof's used-car market: how hidden quality can unravel a market entirely.InteractiveAdvancedMoral HazardHidden actions after the contract is signed, insurance, effort, and incentive design.Coming soonAdvancedSignaling & Screening (Spence)Costly signals that separate types, why education can pay even if it teaches nothing.Coming soonAdvancedAuction 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.InteractiveIntroKeynesian Cross & the MultiplierPlanned spending meets the 45° line, watch a $1 injection multiply into more output.InteractiveIntroPhillips CurveThe inflation-unemployment tradeoff, real in the short run, gone in the long run.InteractiveIntroGDP, Unemployment & Inflation MeasurementHow the headline numbers are actually built: expenditure and income approaches, CPI, labor force stats.Coming soonIntroBusiness Cycle PhasesBoom, peak, recession, trough, the anatomy of fluctuations around trend growth.InteractiveIntroMoney MultiplierHow fractional-reserve banking turns base money into broad money, and the leaks in the process.InteractiveIntroQuantity Theory of Money (MV = PY)The oldest idea in macro: money growth and inflation in the long run.InteractiveIntro
IS-LMGoods market meets money market: fiscal and monetary policy in one diagram.InteractiveIntermediateIS Curve Microfoundations (PIH)Deriving the IS curve properly, including what the Permanent Income Hypothesis does to fiscal policy.Coming soonAdvancedLM Curve / Money Market EquilibriumThe money-market foundations behind the LM curve, explore it live in the Money Market model.InteractiveIntermediateMundell-Fleming (Open-Economy IS-LM)IS-LM with exchange rates: why policy works completely differently under fixed vs. floating regimes.InteractiveAdvancedFisher EquationNominal rates, real rates, and expected inflation, the identity underneath monetary policy.InteractiveIntermediateGovernment Budget Constraint & SeigniorageDeficits, debt dynamics, and the inflation tax when governments print to pay.InteractiveAdvancedSolow-Swan Growth ModelCapital accumulation, diminishing returns, and the steady state, why saving alone can't drive growth forever.InteractiveIntermediateHarrod-Domar Growth ModelThe knife-edge predecessor to Solow: growth from the saving rate and capital-output ratio.InteractiveAdvancedEndogenous Growth (Romer, AK, Lucas)Growth from ideas and human capital, models where the growth rate itself is a choice.InteractiveAdvancedRamsey-Cass-Koopmans ModelSolow with optimizing households: the saving rate chosen by intertemporal utility maximization.Coming soonAdvancedOverlapping Generations ModelYoung savers, old dissavers, a workhorse for pensions, bubbles, and dynamic inefficiency.Coming soonAdvancedGrowth Accounting & the Solow ResidualDecomposing growth into capital, labor, and TFP, the measurement behind the theory.Coming soonAdvancedMalthusian Growth ModelWhy living standards were flat for millennia: population growth eating every productivity gain.InteractiveIntermediateConvergence HypothesisDo poor countries catch up? Absolute vs. conditional convergence and what the data says.InteractiveAdvancedNew Keynesian 3-Equation ModelThe modern central-banking workhorse, its IS block, Phillips curve, and Taylor rule are each interactive here.InteractiveAdvancedTaylor RuleThe interest-rate rule that describes (and prescribes) how central banks respond to inflation and gaps.InteractiveIntermediateReal Business Cycle TheoryBusiness cycles as efficient responses to technology shocks, the provocation that built modern macro.Coming soonAdvancedExpectations-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.InteractiveIntroLabor-Leisure TradeoffWork as a consumer choice: utility maximization with a time constraint, and backward-bending supply.InteractiveIntermediateHuman Capital & the Mincer EquationEducation as investment: how schooling and experience price into earnings.InteractiveIntermediateEfficiency Wage TheoryWhy firms pay above market, morale, effort, and unemployment as a discipline device.Coming soonIntermediateSearch & Matching (DMP)Unemployment as a matching problem: vacancies, job-finding rates, and the Beveridge curve.InteractiveAdvancedBathtub Model of UnemploymentInflows and outflows setting the unemployment rate, the simplest honest model of the labor market.InteractiveIntermediateMonopsony & 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 soonIntermediateHeckscher-Ohlin ModelTrade driven by factor endowments, capital-rich countries export capital-intensive goods.Coming soonAdvancedStolper-Samuelson TheoremTrade's distributional bite: who wins and who loses inside a country when it opens up.Coming soonAdvancedGravity Model of TradeTrade flows predicted by size and distance, the most empirically successful model in economics.InteractiveIntermediatePurchasing Power ParityThe law of one price across borders. Big Mac index logic and long-run exchange rates.InteractiveIntermediateBalance of PaymentsCurrent account, capital account, and why the books always balance.Coming soonIntermediateInterest Rate ParityCovered and uncovered parity: how interest differentials pin down forward exchange rates.InteractiveAdvanced
Money MarketMoney supply meets money demand, how the nominal interest rate is set.InteractiveIntroLoanable Funds MarketSaving supplies funds, investment demands them, the real interest rate clears the market.InteractiveIntroBaumol-Tobin Money DemandCash management as an inventory problem, the square-root rule for money holdings.InteractiveAdvancedCapital Asset Pricing Model (CAPM)Risk priced by beta: the security market line and the cost of equity.InteractiveIntermediateEfficient Market HypothesisPrices as information processors, weak, semi-strong, and strong forms, and the anomalies.Coming soonIntermediateModigliani-Miller TheoremWhy capital structure is irrelevant in frictionless markets, and what the frictions change.Coming soonAdvancedTerm Structure of Interest RatesWhat the yield curve knows: expectations, term premia, and inversion as recession signal.InteractiveAdvancedBlack-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.InteractiveIntermediateClassical Assumptions (Gauss-Markov, BLUE)When OLS is the best you can do, and what breaks when each assumption fails.Coming soonIntermediateInstrumental Variables & 2SLSCausality from clever variation: instruments, relevance, exogeneity, and two-stage least squares.Coming soonAdvancedHausman TestTesting for endogeneity and choosing between estimators. FE vs. RE, OLS vs. IV.Coming soonAdvancedDifference-in-DifferencesPolicy evaluation with a treated and control group, parallel trends and the 2×2 table.InteractiveAdvancedPanel Data (Fixed & Random Effects)Following units over time: sweeping out fixed characteristics to get closer to causality.Coming soonAdvancedRegression Discontinuity DesignCausal effects from cutoffs, comparing people just above and just below a threshold.Coming soonAdvancedTime Series (Unit Roots, Autocorrelation)Dickey-Fuller tests, spurious regression, HAC errors, the hazards of data over time.Coming soonAdvancedTrend vs. Difference StationarityWhether shocks die out or last forever, and why it changes how you model growth.Coming soonAdvancedProbit & 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.InteractiveIntermediateBounded RationalitySatisficing over optimizing, decision-making with limited attention, information, and computation.Coming soonIntermediateHyperbolic Discounting & Present BiasWhy we plan patiently and act impulsively, beta-delta preferences and commitment devices.InteractiveIntermediateNudge Theory & Choice ArchitectureDefaults, framing, and salience: steering choices without restricting them.Coming soonIntroLoss 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 soonAdvancedKuhn-Tucker (KKT) ConditionsOptimization with inequality constraints: complementary slackness and corner solutions.Coming soonAdvancedEnvelope TheoremComparative statics via value functions, the shortcut behind Shephard's and Hotelling's lemmas.Coming soonAdvancedHessian & Bordered HessianSecond-order conditions: checking that your optimum is actually a maximum.Coming soonAdvancedComparative StaticsHow equilibria move when parameters change, practice it live in any interactive model, starting with Supply & Demand.InteractiveIntermediateDynamic Optimization BasicsChoosing over time: Bellman thinking, Euler equations, and the tools behind Ramsey and RBC.Coming soonAdvanced