Frank Cowell: Efficiency-Waste EFFICIENCY: WASTE MICROECONOMICS Principles and Analysis Frank Cowell Almost essential Welfare and Efficiency Almost essential Welfare and Efficiency Prerequisites
Frank Cowell: Efficiency-Waste Agenda Build on the efficiency presentation Focus on relation between competition and efficiency Start from the “standard” efficiency rules MRS same for all households MRT same for all firms MRS=MRT for all pairs of goods What happens if we depart from them? How to quantify departures from them?
Frank Cowell: Efficiency-Waste Basic model Applications Overview… Background Model with production Efficiency: Waste How to evaluate inefficient states
Frank Cowell: Efficiency-Waste The approach Use standard general equilibrium analysis to… Model price distortion Define reference set of prices Use consumer welfare analysis to… Model utility loss Use standard analysis of household budgets to… Model change in profits and rents
Frank Cowell: Efficiency-Waste A reference point Address the question: how much waste? Need a reference point where there is zero waste quantify departures from this point Any efficient point would do But it is usual to take a CE allocation gives us a set of prices we’re not assuming it is the “default” state just a convenient benchmark Can characterise inefficiency as price distortion
Frank Cowell: Efficiency-Waste = p 1 ~ p1p1 [1 = p 2 ~ p2p2 = p 3 ~ p3p3 pnpn = …… = p n ~ consumer prices firms' prices But now we have a distortion A model of price distortion Assume there is a competitive equilibrium If so, then everyone pays the same prices What are the implications for MRS and MRT? Distortion
Frank Cowell: Efficiency-Waste Price distortion: MRS and MRT Consumption: p j MRS ij h = — p i For every household marginal rate of substitution = price ratio Production: for commodities 2,3,…,n p j MRT n j = — p n p j MRT 3 j = — p 3 p j MRT 2 j = — p 2 p j MRT 1 j = — p 1 [1+ ] … … … But for commodity 1… Illustration…
Frank Cowell: Efficiency-Waste x1x1 0 x2x2 Consumers Price distortion: efficiency loss Production possibilities An efficient allocation Some other inefficient allocation How to measure importance of this wedge … x x* p* Producers At x * producers and consumers face same prices At x producers and consumers face different prices Price "wedge" forced by the distortion
Frank Cowell: Efficiency-Waste Waste measurement: a method To measure loss we use a reference point Take this as competitive equilibrium… …which defines a set of reference prices Quantify the effect of a notional price change: p i := p i – p i * This is [actual price of i] – [reference price of i] Evaluate the equivalent variation for household h : EV h = C h (p*, h ) – C h (p, h ) – [y* h – y h ] This is (consumer costs) – (income) Aggregate over agents to get a measure of loss, We do this for two cases…
Frank Cowell: Efficiency-Waste Basic model Applications Overview… Background Model with production Efficiency: Waste Taking producer prices as constant…
Frank Cowell: Efficiency-Waste x1x1 0 x2x2 If producer prices constant… Production possibilities Reference allocation and prices Actual allocation and prices x x* p* Measure cost in terms of good 2 Losses to consumers are C(p*, ) C(p, ) Cost of at prices p C(p, ) l Cost of at prices p* l C(p*, ) Change in valuation of output p p is difference between C(p*, ) C(p, ) and
Frank Cowell: Efficiency-Waste Model with fixed producer prices Waste involves both demand and supply responses Simplify by taking case where production prices constant Then waste is given by: Use Shephard’s Lemma x i h = H hi (p, h ) = C i h (p, h ) Take a Taylor expansion to evaluate : is a sum of areas under compensated demand curve
Frank Cowell: Efficiency-Waste Basic model Applications Overview… Background Model with production Efficiency: Waste Allow supply-side response…
Frank Cowell: Efficiency-Waste x1x1 0 x2x2 Waste measurement: general case Production possibilities Reference allocation and prices Actual allocation and prices x* p* Measure cost in terms of good 2 Losses to consumers are C(p*, ) C(p, ) Cost of at prices p C(p, ) l Cost of at prices p* l C(p*, ) Change in valuation of output p p is difference between C(p*, ) C(p, ) and x
Frank Cowell: Efficiency-Waste Model with producer price response Adapt the formula to allow for supply responses Then waste is given by: where q i (∙) is net supply function for commodity i Again use Shephard’s Lemma and a Taylor expansion:
Frank Cowell: Efficiency-Waste Basic model Applications Overview… Background Model with production Efficiency: Waste Working out the hidden cost of taxation and monopoly…
Frank Cowell: Efficiency-Waste Application 1: commodity tax Commodity taxes distort prices Take the model where producer prices are given Let price of good 1 be forced up by a proportional commodity tax t Use the standard method to evaluate waste What is the relationship of tax to waste? Simplified model: identical consumers no cross-price effects… …impact of tax on good 1 does not affect demand for other goods Use competitive, non-distorted case as reference:
Frank Cowell: Efficiency-Waste A model of a commodity tax p1p1 compensated demand curve p1p1 p1*p1* x1hx1h x1hx1h x1*x1* revenue raised = tax x quantity revenue raised = tax x quantity Equilibrium price and quantity The tax raises consumer price… …and reduces demand Gain to the government Loss to the consumer Waste Waste given by size of triangle Sum over h to get total waste Known as deadweight loss of tax
Frank Cowell: Efficiency-Waste Tax: computation of waste An approximation using Consumer’s Surplus The tax imposed on good 1 forces a price wedge p 1 = tp 1 * > 0 where is p 1 * is the untaxed price of the good h’s demand for good 1 is lower with the tax: x 1 ** rather than x 1 * where x 1 ** = x 1 * x 1 h and x 1 h < 0 Revenue raised by government from h: T h = tp 1 * x 1 ** = x 1 ** p 1 > 0 Absolute size of loss of consumer’s surplus to h is CS h = ∫ x 1 h dp 1 ≈ x 1 ** p 1 − ½ x 1 h p 1 = T h − ½ t p 1 * x 1 h > T h Use the definition of elasticity := p 1 x 1 h / x 1 h p 1 < 0 Net loss from tax (for h) is h = CS h − T h = − ½tp 1 * x 1 h = − ½t p 1 x 1 ** = − ½t T h Overall net loss from tax (for h) is ½ | tT uses the assumption that all consumers are identical
Frank Cowell: Efficiency-Waste p1p1 compensated demand curve p1p1 p1*p1* x1hx1h x1hx1h Size of waste depends upon elasticity low: relatively small waste high: relatively large waste Redraw previous example p1p1 p1p1 p1*p1* x1hx1h x1hx1h p1p1 p1p1 p1*p1* x1hx1h x1hx1h p1p1 p1p1 p1*p1* x1hx1h x1hx1h
Frank Cowell: Efficiency-Waste Application 1: assessment Waste inversely related to elasticity Low elasticity: waste is small High elasticity: waste is large Suggests a policy rule suppose required tax revenue is given which commodities should be taxed heavily? if you just minimise waste – impose higher taxes on commodities with lower elasticities In practice considerations other than waste-minimisation will also influence tax policy distributional fairness among households administrative costs
Frank Cowell: Efficiency-Waste Application 2: monopoly Monopoly power is supposed to be wasteful… but why? We know that monopolist… charges price above marginal cost so it is inefficient … …but how inefficient? Take simple version of main model suppose markets for goods 2, …, n are competitive good 1 is supplied monopolistically
Frank Cowell: Efficiency-Waste Monopoly: computation of waste (1) Monopoly power in market for good 1 forces a price wedge p 1 = p 1 * * − p 1 * > 0 where p 1 ** is price charged in market p 1 * is marginal cost (MC) h’s demand for good 1 is lower under this monopoly price: x 1 ** x 1 * x 1 h, where x 1 h < 0 Same argument as before gives: loss imposed on household h: −½ p 1 x 1 h > 0 loss overall: − ½ p 1 x 1, where x 1 is total output of good 1 using definition of elasticity , loss equals − ½ p 1 2 x 1 * * p 1 * * To evaluate this need to examine monopolist’s action…
Frank Cowell: Efficiency-Waste Monopoly: computation of waste (2) Monopolist chooses overall output use first-order condition MR = MC: Evaluate MR in terms of price and elasticity: p 1 * * [ / ] FOC is therefore p 1 * * [ / ] = MC hence p 1 = p 1 * * − MC = − p 1 * * / Substitute into triangle formula to evaluate measurement of loss: ½ p 1 * * x 1 * * / | Waste from monopoly is greater, the more inelastic is demand Highly inelastic demand: substantial monopoly power Elastic demand: approximates competition
Frank Cowell: Efficiency-Waste Summary Starting point: an “ideal” world pure private goods no externalities etc so CE represents an efficient allocation Characterise inefficiency in terms of price distortion in the ideal world MRS = MRT for all h, f and all pairs of goods Measure waste in terms of income loss fine for individual OK just to add up? Extends to more elaborate models straightforward in principle but messy maths Applications focus on simple practicalities elasticities measuring consumers’ price response but simple formulas conceal strong assumptions