【正文】 f a tax is small. 圖 5. 稅收扭曲與彈性 (a) 缺乏彈性的供給 價(jià)格 0 數(shù)量 需求 供給 稅收規(guī)模 當(dāng)供給比較缺乏 彈性時(shí)，稅收的 無謂損失小。 2023 Thomson SouthWestern THE DETERMINANTS OF THE DEADWEIGHT LOSS ? The greater the elasticities of demand and supply: – the larger will be the decline in equilibrium quantity and, – the greater the deadweight loss of a tax. 169。 2023 Thomson SouthWestern 無謂損失和稅收收入隨稅收變動而變動 ? 無謂損失的爭論 – 一些經(jīng)濟(jì)學(xué)家認(rèn)為勞動稅引起嚴(yán)重扭曲，他們相信勞動供給是較為富有彈性的 . – 一些對激勵(lì)反應(yīng)較大的工人 : ? 許多可以調(diào)整工作時(shí)間長短的工人 ? 一些有第二個(gè)賺錢人的家庭 ? 許多老年人可以選擇什么時(shí)候退休 ? 從事地下經(jīng)濟(jì)活動的工人 (如從事非法活動的人 ) 169。 2023 Thomson SouthWestern DEADWEIGHT LOSS AND TAX REVENUE AS TAXES VARY ? For the small tax, tax revenue is small. ? As the size of the tax rises, tax revenue grows. ? But as the size of the tax continues to rise, tax revenue falls because the higher tax reduces the size of the market. 169。 Figure 6 How Deadweight Loss and Tax Revenue Vary with the Size of a Tax (a) Deadweight Loss Deadweight Loss 0 Tax Size 圖 6. 無謂損失和稅收收入如何隨著稅收規(guī)模而變動 (a) 無謂損失 無謂損失 0 稅收規(guī)模 Figure 6 How Deadweight Loss and Tax Revenue Vary with the Size of a Tax (b) Revenue (the Laffer curve) Tax Revenue 0 Tax Size 圖 6. 無謂損失和稅收收入如何隨著稅收規(guī)模而變動 (b) 稅收收入（拉伐曲線） 稅收收入 0 稅收規(guī)模 169。 Summary 169。 Summary 169。 Summary 169。 ? 但是，最終由于高稅收減少了市場規(guī)模，也就減少了稅收收入。 2023 Thomson SouthWestern 應(yīng)用：國際貿(mào)易 ? 什么決定一個(gè)國家是否進(jìn)口或 出口一種物品 ? ? 在國際自由貿(mào)易中誰獲 利誰虧損？ ? 人們用來支持貿(mào)易限制的 各種觀點(diǎn)是什么？ 169。 2023 Thomson SouthWestern 沒有貿(mào)易時(shí)的均衡 ? 結(jié)果 : ? 國內(nèi)價(jià)格調(diào)整使國內(nèi)賣者的供給量與國內(nèi)買者的需求量平衡。 2023 Thomson SouthWestern The World Price and Comparative Advantage ? The effects of free trade can be shown by paring the domestic price of a good without trade and the world price of the good. The world price refers to the price that prevails in the world market for that good. 169。 2023 Thomson SouthWestern The World Price and Comparative Advantage ? If a country has a parative advantage, then ? the domestic price will be below the world price, and ? the country will be an exporter of the good. ? If the count。 ? 世界價(jià)格 ——一種物品在世界市場上所流行的價(jià)格。 169。 2023 Thomson SouthWestern 貿(mào)易的決定因素 ? 沒有貿(mào)易時(shí)的均衡 –假定 : ? 一個(gè)生產(chǎn)鋼鐵的國家孤立于其他國家 ? 鋼鐵市場由這個(gè)國家的買者和賣者組成 ? 這個(gè)國家的如何人都不允許進(jìn)口或出口鋼鐵 Figure 1 The Equilibrium without International Trade Consumer surplus Producer surplus Price of Steel 0 Quantity of Steel Domestic supply Domestic demand Equilibrium price Equilibrium quantity 圖 1. 沒有國際貿(mào)易時(shí)的均衡 鋼鐵的 價(jià)格 均衡價(jià)格 0 鋼鐵數(shù)量 均衡數(shù)量 國內(nèi)供給 國內(nèi)需求 生產(chǎn)者剩余 消費(fèi)者剩余 169。 2023 Thomson SouthWestern 應(yīng)用：國際貿(mào)易 169。 2023 Thomson SouthWestern ? 隨著稅收增加，它對激勵(lì)的扭曲越來越大，而且無謂損失也越來越大。 2023 Thomson SouthWestern ? 稅收有無謂損失是因?yàn)樗鹳I者少消費(fèi)和賣者少生產(chǎn)。 2023 Thomson SouthWestern ? 向一種物品征稅減少了該物品買者與賣者的福利，而且消費(fèi)者和生產(chǎn)者剩余的減少通常超過了政府籌集到的收入。 2023 Thomson SouthWestern 無謂損失和稅收收入隨稅收變動而變動 ? 隨著稅收規(guī)模提高，無謂損失迅速增大。 ? 隨著稅收規(guī)模增加，稅收收入增加。 2023 Thomson SouthWestern 無謂損失和稅收收入隨稅收規(guī)模而變動 ? 隨著每一次稅率增加，稅收無謂損失的增加要快于稅收規(guī)模。 169。 Figure 5 Tax Distortions and Elasticities (d) Elastic Demand Price 0 Quantity Size of tax Demand Supply When demand is relatively elastic, the deadweight loss of a tax is large. 圖 5. 稅收扭曲與彈性 (d) 富有彈性的需求 價(jià)格 0 數(shù)量 稅收 規(guī)模 需求 供給 當(dāng)需求比較富有彈性時(shí)， 稅收的無謂損失大。 2023 Thomson SouthWestern 無謂損失的決定因素 ? 什么因素決定稅收的無謂損失是大還是??？ –無謂損失的大小決定于供給量和需求量對價(jià)格變動的反應(yīng)程度。 2023 Thomson SouthWestern Deadweight Losses and the Gains from Trade ? Taxes cause deadweight losses because they prevent buyers and sellers from realizing some of the gains from trade. 169。 2023 Thomson SouthWestern 稅收如何影響市場參與者 ? 福利的變化 ? 無謂損失 ——市場扭曲（比如收稅）引起的總剩余減少。 2023 Thomson SouthWestern How a Tax Affects Market Participants ? Tax Revenue ? T = the size of the tax ? Q = the quantity of the good sold ? T ? Q = the government’ s tax revenue 169。 2023 Thomson SouthWestern How a Tax Affects Market Participants ? A tax places a wedge between the price buyers pay and the price sellers receive. ? Because of this tax wedge, the quantity sold falls below the level that would be sold without a tax. ? The size of the market for that good shrinks. 169。 2023 Thomson SouthWestern 稅收的無謂損失 ? 稅收如何影響市場參與者的經(jīng)濟(jì)福利 ? 169。 –買者和賣者可以從參與市場活動中獲得利益。 169。 2023 Thomson SouthWestern ? The equilibrium of demand and supply maximizes the sum of consumer and producer surplus. ? This is as if the invisible hand of the marketplace leads buyers and sellers to allocate resources efficiently. ? Markets do not allocate resources efficiently in the presence of market failures. Summary 169。 2023 Thomson SouthWestern ? An allocation of resources that maximizes the sum of consumer and producer surplus is said to be efficient. ? Policymakers are often concerned with the efficiency, as well as the equity, of economic outes. Summary 169。 2023 Thomson SouthWestern ? 生產(chǎn)者剩余等于賣者出售某種物品得到的量減去賣者的生產(chǎn)成本。 ? 消費(fèi)者剩余衡量買者從參與市場中得到的利益。 ? 在買者決定消費(fèi)量和賣者決定生產(chǎn)量而不考慮外部性時(shí)，市場均衡可能是無效率的。 169。 2023 Thomson SouthWestern Evaluating the Market Equilibrium ? Market Power ? If a market system is not perfectly petitive, market power may result. ? Market power is the ability to influence prices. ? Market power can cause markets to be inefficient because it keeps price and quantity from the equilibrium of supply and demand. 169。 2023 Thomson SouthWestern Evaluating the Market Equilibrium ? Because the equilibrium oute is an efficient allocation of resources, the social planner can leave the market oute as he/she finds it. ? This policy of leaving well enough alone goes by the French expression laissez faire. 169。 2023 Thomson SouthWestern 市場均衡的評價(jià) ? 三種關(guān)于市場結(jié)果的觀點(diǎn) ? 自由市場把物品的供給分配給對這些物品評價(jià)最高的買者。 2023 Thomson SouthWestern The Benevolent Social Planner ? In additi