【正文】
This is as if the invisible hand of the marketplace leads buyers and sellers to allocate resources efficiently. ? 當有市場勢力和外部性時,市場不能有效率地配置資源。 An allocation of resources that maximizes the sum of consumer and producer surplus is said to be efficient. ? 政策制定者通常關(guān)心經(jīng)濟的效率問題,但同時也關(guān)心平等問題。 Producer surplus measures the benefit sellers get from participating in a market. ? 生產(chǎn)者剩余可以通過找出價格以下和供給曲線以上的面積來計算。 Consumer surplus measures the benefit buyers get from participating in a market. ? 消費者剩余可以通過找出需求曲線以下和價格以上的面積來計算。 Externalities cause welfare in a market to depend on more than just the value to the buyers and cost to the sellers. ? 當買者和賣者在決定消費和生產(chǎn)時不考慮外部性的時候,市場均衡可能是無效率的。 Market power is the ability to influence prices. ? 市場勢力可以使市場無效率,因為它會使價格和數(shù)量偏離供求均衡點。 市場勢力 Market Power ? 如果市場不完全競爭,市場勢力便形成。 為什么關(guān)于市場有效率的模型 如此重要,盡管假設(shè)與現(xiàn)實會有距離 ? 當這些假設(shè)成立的時候,關(guān)于市場均衡有效率的結(jié)論成立 ? 即使在現(xiàn)實中這些假設(shè)不完全成立,它仍然為我們分析問題提供了一個基準或標尺(benchmark)或稱參照系 (reference) ? 有了這一基準或標尺,我們對現(xiàn)實的進一步分析就有力量。 (Market power) ?市場結(jié)果只與買者和賣者相關(guān),即無外部性(externalities) 。 ? 當這些假設(shè)不成立的時候,關(guān)于市場均衡有效率的結(jié)論可能就不成立了。通過收取市場可以承受的最高價格,倒票者有助于保證對門票支付意愿最高的人實際上得到這些票。 In addition to market efficiency, a social planner might also care about equity – the fairness of the distribution of wellbeing among the various buyers and sellers. 例子:倒賣門票 Example: Ticket Scalping ? 如果一個經(jīng)濟能有效地配置其稀缺資源,物品必須給與對此評價最高的那些消費者。 Because the equilibrium oute is an efficient allocation of resources, the social planner can leave the market oute as he/she finds it. ? 這種完全放開的政策可以用法語自由放任來表述。 If an allocation is not efficient, then some of the gains from trade among buyers and sellers are not being realized. ? 市場配置是有效率的,因為它實現(xiàn)了所有的貿(mào)易好處。這個結(jié)論解釋了經(jīng)濟學(xué)家通常支持自由市場是組織經(jīng)濟活動的最好方法的原因。斯密的市場這只看不見的手。換句話說,均衡結(jié)果是資源的有效配置。 Free markets allocate the supply of goods to the buyers who value them most highly. ? 自由市場把物品的需求分配給可以以最低成本生產(chǎn)這些物品的賣者。 Efficiency is achieved when the allocation of resources maximizes total surplus. 如果你是一個仁慈的社會計劃者, 你將進行怎樣的配置以達到效率? 效率 Efficiency ? 條件 1:在給定的數(shù)量下,一種物品的分配使得它: ?由最低成本的那些賣者來生產(chǎn); ?由最高評價(支付意愿)的那些買者來消費 ? 條件 2:給定上述的分配方案,該物品的數(shù)量是使得總剩余最大的數(shù)量。 At any quantity, the price given by the supply curve shows the cost of the marginal seller, the seller who would leave the market first if the price were any lower. 四個賣者的供給量 Supply Schedule for the Four Possible Sellers 價格 Pri ce 賣者 Sell ers 供給量Qu an ti ty Su p p l i ed $900 or mo re M ary , Fri da , G eo r g i a, G r an dma 4 $800 to $ 900 Fri da , G eo r g i a, G r an dma 3 $600 to $ 800 G eo r g i a,