双语：可乐价格为何60年不变？

　　UNDERCOVER ECONOMIST: FOR BETTER OR WORTH

　　The price of the first serving of Coca-Cola was five centsin1886, which is about a dollar (50p) in todays money. Cokenolonger sells for a nickel, and that is not terriblysurprising.What is surprising is that it took more than 60 yearsfor the priceof Coca-Cola to change.

　　Economists call this nominal price rigidity. My salary isnottweaked each month to reflect the latest inflation figures,andneither is yours. Restaurants do not reprint their menus,norwholesale companies their catalogues, if the cost of theirinputschanges by a penny.

　　That might be a problem. Prices keep the economy runningsmoothlyby adjusting to reflect demand and the underlying costsofproduction. If prices dont adjust smoothly for any reason thentheeconomic consequences could be serious. If wages cant fall inarecession then people will lose their jobs instead. If pricescantfall when demand does, sales will collapse with much thesameeffect.

　　Coke was clearly an exceptional example of rigid prices.DanielLevy and Andrew Young, the economists who analysed the case,reportthat Cokes price stayed at five cents a serving while theprice ofother products bounced all over the place. The price ofsugartripled after the first world war before falling backsomewhat;over the six decades, the price of coffee went upeightfold. Cokeitself was taxed first as a medicine, then as a softdrink, andsurvived sugar rationing. All the while the price stayedat anickel.

　　Part of Cokes problem was the cost of replacing vendingmachinesthat accepted only nickels - and the fact that thealternative,dimes, represented a 100 per cent price hike. (The bossofCoca-Cola wrote to his friend President Eisenhower in 1953tosuggest, in all seriousness, a 7.5 cent coin.)

　　Most companies dont wait so long to change prices if theyneedto. Researchers have tended to conclude that many priceschangeevery year or so, and often sooner. Levy and some colleagueslookedat supermarket pricing in the mid-1990s and found, basedondetailed accounting data, that to change the price of a singletypeof product in a typical supermarket cost 52 cents inprinting,labour and errors. The total of all such changes was about$100,000per store per year - still less than one per cent ofrevenue.

　　Technology makes it ever easier to change prices using barcodes,websites, and laser-printed menus. Amazon always seems tobechanging book prices. Coke vending machines now take verylittleeffort to reprogram. So should we conclude that ”menu costs”nolonger matter?

　　That would be too optimistic. Economists have long arguedthateven small ”menu costs” could cause large economicdistortions,because when companies are pondering whether to paythose costs,they dont consider the social benefits of a moreaccurate price,only their own profits.

　　A prize-winning paper from Carlos Carvalho recently showed thatitdoes not even help if many prices adjust quickly, because thosethatchange slowly will distort the rest. Amazon may be able toadjustits prices easily to reflect its costs, but that is littleuse ifthose costs are distorted by slow adjustments from, say,thebookbinders or the freight handlers.

　　Coca-Colas experience reflected exactly that: long beforetheintroduction of vending machines, they had signed aperpetualfixed-price contract to supply their bottlers, at a timeof verylow inflation.

　　I drank a 500ml bottle of Coke while writing this article, anditcost me 85p ($1.70) from the corner shop. Id rather have paidanickel, but price changes are important. Perhaps I shouldnt betooungrateful. (接下页)

　　 可乐价格为何60年不变？

　　1886年，一罐可口可乐(Coca-Cola)的价格是5美分，大约相当于今天的1美元（50便士）。

如今的可乐售价不再是5美分了，而这并不特别令人惊诧。真正令人惊诧的是，可口可乐的价格用了60多年的时间才发生变化。

　　经济学家将这称为名义价格刚性。我的工资并非每个月进行调整，以反映最新的通货膨胀数据；你的工资也一样。如果原材料成本发生一分钱的变化，餐馆不会重新印制菜单，批发公司也不会修改商品目录。

　　这可能是个问题。价格之所以能够保持经济平稳运行，是因为它会做出调整，以反映需求和潜在的生产成本。如果价格因为某种原因而没有进行平稳调整，那就可能造成非常严重的经济后果。经济衰退时，如果工资未能下降，那么人们将会失业。需求下降时，如果价格不能下跌，那么销售将崩溃，结果还是一样。

　　可乐显然是价格刚性的一个突出案例。经济学家丹尼尔·利维(DanielLevy)和安德鲁·杨(AndrewYoung)对此进行了分析。他们撰写报告称，当其它商品价格都在上涨时，可乐价格一直保持每罐5美分。糖价在第一次世界大战后上涨了两倍，然后略有回落；在60年期间里，咖啡价格上涨7倍。可乐本身最早作为一种药品纳税，然后作为软饮料纳税，还承受了糖配给供应。但自始至终，它的价格都保持在5美分。

　　可乐的价格问题，部分在于更换自动售货机的成本（这些机器只接受5分镍币），以及若改为接受一角硬币，意味着价格将上涨100%。（可口可乐的老板曾于1953年写信给他的朋友、美国总统艾森豪威尔，非常严肃地建议使用7.5美分的硬币。）

　　对于多数公司而言，如果有必要改变价格，它们一般不会等太久。研究者往往得出结论称，许多商品价格变化的周期是一年左右，往往还会更快一些。利维和一些同事考查了上世纪90年代中期的超市定价，在详细研究了会计数据后发现，一家典型的超市要改变某类商品的价格，需要在印刷、劳动力和误差方面花费52美分的成本。一家商店每年进行价格变化的总成本为10万美元——仍不足其营业收入的1%。

　　运用条形码、网站和激光打印的菜单，科技使得调价变得更容易。亚马逊(Amazon)似乎总是在改变图书的价格。如今，改编可乐售货机的程序几乎不用费什么力气。因此，我们是否应该得出“菜单成本”(menucosts)不再重要的结论呢？

　　这一看法可能过于乐观。经济学家长期以来一直主张，即便是微小的“菜单成本”也可能导致严重的经济扭曲，原因是当企业考虑是否支付这些成本时，它们想到的只是自己的利润，而不会考虑提高价格准确性所带来的社会利益。

　　卡洛斯·卡瓦略(CarlosCarvalho)最近获奖的一篇论文表明，即便是许多商品价格进行了迅速调整，结果也无济于事，因为变动缓慢的价格将会扭曲其它价格。亚马逊或许能够轻松调整图书价格，以反映其成本，但如果图书装订商或货运商的价格调整缓慢，导致这些成本扭曲，那么，亚马逊的做法就没什么作用。

　　可口可乐的案例反映的正是这种情况：早在引入售货机之前很久，该公司就在通胀非常低的时候签署了长期的固定价格合同，向罐装商供应可乐。

　　在撰写本文时，我喝掉了一瓶500毫升的可乐。这是我从街角的商店以85便士（合1.70美元）的价格买的。我宁愿付的是5美分，但价格变化非常重要。或许我不应该太不知感激。(编辑:HD)

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