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UNDERCOVER ECONOMIST: FOR BETTER OR WORTH
可樂價格為何60年不變？
The price of the first serving of Coca-Cola was five cents in 1886, which is about a dollar (50p) in today's money. Coke no longer sells for a nickel, and that is not terribly surprising. What is surprising is that it took more than 60 years for the price of Coca-Cola to change.
1886年，一罐可口可樂(Coca-Cola)的價格是5美分，大約相當于今天的1美元（50便士）。如今的可樂售價不再是5美分了，而這并不特別令人驚詫。真正令人驚詫的是，可口可樂的價格用了60多年的時間才發生變化。
Economists call this nominal price rigidity. My salary is not tweaked each month to reflect the latest inflation figures, and neither is yours. Restaurants do not reprint their menus, nor wholesale companies their catalogues, if the cost of their inputs changes by a penny.
經濟學家將這稱為名義價格剛性。我的工資并非每個月進行調整，以反映最新的通貨膨脹數據；你的工資也一樣。如果原材料成本發生一分錢的變化，餐館不會重新印制菜單，批發公司也不會修改商品目錄。
That might be a problem. Prices keep the economy running smoothly by adjusting to reflect demand and the underlying costs of production. If prices don't adjust smoothly for any reason then the economic consequences could be serious. If wages can't fall in a recession then people will lose their jobs instead. If prices can't fall when demand does, sales will collapse with much the same effect.
這可能是個問題。價格之所以能夠保持經濟平穩運行，是因為它會做出調整，以反映需求和潛在的生產成本。如果價格因為某種原因而沒有進行平穩調整，那就可能造成非常嚴重的經濟后果。經濟衰退時，如果工資未能下降，那么人們將會失業。需求下降時，如果價格不能下跌，那么銷售將崩潰，結果還是一樣。
Coke was clearly an exceptional example of rigid prices. Daniel Levy and Andrew Young, the economists who analysed the case, report that Coke's price stayed at five cents a serving while the price of other products bounced all over the place. The price of sugar tripled after the first world war before falling back somewhat; over the six decades, the price of coffee went up eightfold. Coke itself was taxed first as a medicine, then as a soft drink, and survived sugar rationing. All the while the price stayed at a nickel.
可樂顯然是價格剛性的一個突出案例。經濟學家丹尼爾•利維(Daniel Levy)和安德魯•楊(Andrew Young)對此進行了分析。他們撰寫報告稱，當其它商品價格都在上漲時，可樂價格一直保持每罐5美分。糖價在第一次世界大戰后上漲了兩倍，然后略有回落；在60年期間里，咖啡價格上漲7倍。可樂本身最早作為一種藥品納稅，然后作為軟飲料納稅，還承受了糖配給供應。但自始至終，它的價格都保持在5美分。
Part of Coke's problem was the cost of replacing vending machines that accepted only nickels - and the fact that the alternative, dimes, represented a 100 per cent price hike. (The boss of Coca-Cola wrote to his friend President Eisenhower in 1953 to suggest, in all seriousness, a 7.5 cent coin.)
可樂的價格問題，部分在于更換自動售貨機的成本（這些機器只接受5分鎳幣），以及若改為接受一角硬幣，意味著價格將上漲100%。（可口可樂的老板曾于1953年寫信給他的朋友、美國總統艾森豪威爾，非常嚴肅地建議使用7.5美分的硬幣。）
Most companies don't wait so long to change prices if they need to. Researchers have tended to conclude that many prices change every year or so, and often sooner. Levy and some colleagues looked at supermarket pricing in the mid-1990s and found, based on detailed accounting data, that to change the price of a single type of product in a typical supermarket cost 52 cents in printing, labour and errors. The total of all such changes was about $100,000 per store per year - still less than one per cent of revenue.
對于多數公司而言，如果有必要改變價格，它們一般不會等太久。研究者往往得出結論稱，許多商品價格變化的周期是一年左右，往往還會更快一些。利維和一些同事考查了上世紀90年代中期的超市定價，在詳細研究了會計數據后發現，一家典型的超市要改變某類商品的價格，需要在印刷、勞動力和誤差方面花費52美分的成本。一家商店每年進行價格變化的總成本為10萬美元——仍不足其營業收入的1%。
Technology makes it ever easier to change prices using bar codes, websites, and laser-printed menus. Amazon always seems to be changing book prices. Coke vending machines now take very little effort to reprogram. So should we conclude that ”menu costs” no longer matter?
運用條形碼、網站和激光打印的菜單，科技使得調價變得更容易。亞馬遜(Amazon)似乎總是在改變圖書的價格。如今，改編可樂售貨機的程序幾乎不用費什么力氣。因此，我們是否應該得出“菜單成本”(menu costs)不再重要的結論呢？
That would be too optimistic. Economists have long argued that even small ”menu costs” could cause large economic distortions, because when companies are pondering whether to pay those costs, they don't consider the social benefits of a more accurate price, only their own profits.
這一看法可能過于樂觀。經濟學家長期以來一直主張，即便是微小的“菜單成本”也可能導致嚴重的經濟扭曲，原因是當企業考慮是否支付這些成本時，它們想到的只是自己的利潤，而不會考慮提高價格準確性所帶來的社會利益。
A prize-winning paper from Carlos Carvalho recently showed that it does not even help if many prices adjust quickly, because those that change slowly will distort the rest. Amazon may be able to adjust its prices easily to reflect its costs, but that is little use if those costs are distorted by slow adjustments from, say, the bookbinders or the freight handlers.
卡洛斯•卡瓦略(Carlos Carvalho)最近獲獎的一篇論文表明，即便是許多商品價格進行了迅速調整，結果也無濟于事，因為變動緩慢的價格將會扭曲其它價格。亞馬遜或許能夠輕松調整圖書價格，以反映其成本，但如果圖書裝訂商或貨運商的價格調整緩慢，導致這些成本扭曲，那么，亞馬遜的做法就沒什么作用。
Coca-Cola's experience reflected exactly that: long before the introduction of vending machines, they had signed a perpetual fixed-price contract to supply their bottlers, at a time of very low inflation.
可口可樂的案例反映的正是這種情況：早在引入售貨機之前很久，該公司就在通脹非常低的時候簽署了長期的固定價格合同，向罐裝商供應可樂。
I drank a 500ml bottle of Coke while writing this article, and it cost me 85p ($1.70) from the corner shop. I'd rather have paid a nickel, but price changes are important. Perhaps I shouldn't be too ungrateful.
在撰寫本文時，我喝掉了一瓶500毫升的可樂。這是我從街角的商店以85便士（合1.70美元）的價格買的。我寧愿付的是5美分，但價格變化非常重要。或許我不應該太不知感激。
可樂價格為何60年不變？
| 作者：英國《金融時報》專欄作家蒂姆•哈福德(Tim Harford) |
| 2007年5月15日 星期二 |
The price of the first serving of Coca-Cola was five cents in 1886, which is about a dollar (50p) in today's money. Coke no longer sells for a nickel, and that is not terribly surprising. What is surprising is that it took more than 60 years for the price of Coca-Cola to change.
1886年，一罐可口可樂(Coca-Cola)的價格是5美分，大約相當于今天的1美元（50便士）。如今的可樂售價不再是5美分了，而這并不特別令人驚詫。真正令人驚詫的是，可口可樂的價格用了60多年的時間才發生變化。
Economists call this nominal price rigidity. My salary is not tweaked each month to reflect the latest inflation figures, and neither is yours. Restaurants do not reprint their menus, nor wholesale companies their catalogues, if the cost of their inputs changes by a penny.
經濟學家將這稱為名義價格剛性。我的工資并非每個月進行調整，以反映最新的通貨膨脹數據；你的工資也一樣。如果原材料成本發生一分錢的變化，餐館不會重新印制菜單，批發公司也不會修改商品目錄。
That might be a problem. Prices keep the economy running smoothly by adjusting to reflect demand and the underlying costs of production. If prices don't adjust smoothly for any reason then the economic consequences could be serious. If wages can't fall in a recession then people will lose their jobs instead. If prices can't fall when demand does, sales will collapse with much the same effect.
這可能是個問題。價格之所以能夠保持經濟平穩運行，是因為它會做出調整，以反映需求和潛在的生產成本。如果價格因為某種原因而沒有進行平穩調整，那就可能造成非常嚴重的經濟后果。經濟衰退時，如果工資未能下降，那么人們將會失業。需求下降時，如果價格不能下跌，那么銷售將崩潰，結果還是一樣。
Coke was clearly an exceptional example of rigid prices. Daniel Levy and Andrew Young, the economists who analysed the case, report that Coke's price stayed at five cents a serving while the price of other products bounced all over the place. The price of sugar tripled after the first world war before falling back somewhat; over the six decades, the price of coffee went up eightfold. Coke itself was taxed first as a medicine, then as a soft drink, and survived sugar rationing. All the while the price stayed at a nickel.
可樂顯然是價格剛性的一個突出案例。經濟學家丹尼爾•利維(Daniel Levy)和安德魯•楊(Andrew Young)對此進行了分析。他們撰寫報告稱，當其它商品價格都在上漲時，可樂價格一直保持每罐5美分。糖價在第一次世界大戰后上漲了兩倍，然后略有回落；在60年期間里，咖啡價格上漲7倍。可樂本身最早作為一種藥品納稅，然后作為軟飲料納稅，還承受了糖配給供應。但自始至終，它的價格都保持在5美分。
Part of Coke's problem was the cost of replacing vending machines that accepted only nickels - and the fact that the alternative, dimes, represented a 100 per cent price hike. (The boss of Coca-Cola wrote to his friend President Eisenhower in 1953 to suggest, in all seriousness, a 7.5 cent coin.)
可樂的價格問題，部分在于更換自動售貨機的成本（這些機器只接受5分鎳幣），以及若改為接受一角硬幣，意味著價格將上漲100%。（可口可樂的老板曾于1953年寫信給他的朋友、美國總統艾森豪威爾，非常嚴肅地建議使用7.5美分的硬幣。）
Most companies don't wait so long to change prices if they need to. Researchers have tended to conclude that many prices change every year or so, and often sooner. Levy and some colleagues looked at supermarket pricing in the mid-1990s and found, based on detailed accounting data, that to change the price of a single type of product in a typical supermarket cost 52 cents in printing, labour and errors. The total of all such changes was about $100,000 per store per year - still less than one per cent of revenue.
對于多數公司而言，如果有必要改變價格，它們一般不會等太久。研究者往往得出結論稱，許多商品價格變化的周期是一年左右，往往還會更快一些。利維和一些同事考查了上世紀90年代中期的超市定價，在詳細研究了會計數據后發現，一家典型的超市要改變某類商品的價格，需要在印刷、勞動力和誤差方面花費52美分的成本。一家商店每年進行價格變化的總成本為10萬美元——仍不足其營業收入的1%。
Technology makes it ever easier to change prices using bar codes, websites, and laser-printed menus. Amazon always seems to be changing book prices. Coke vending machines now take very little effort to reprogram. So should we conclude that ”menu costs” no longer matter?
運用條形碼、網站和激光打印的菜單，科技使得調價變得更容易。亞馬遜(Amazon)似乎總是在改變圖書的價格。如今，改編可樂售貨機的程序幾乎不用費什么力氣。因此，我們是否應該得出“菜單成本”(menu costs)不再重要的結論呢？
That would be too optimistic. Economists have long argued that even small ”menu costs” could cause large economic distortions, because when companies are pondering whether to pay those costs, they don't consider the social benefits of a more accurate price, only their own profits.
這一看法可能過于樂觀。經濟學家長期以來一直主張，即便是微小的“菜單成本”也可能導致嚴重的經濟扭曲，原因是當企業考慮是否支付這些成本時，它們想到的只是自己的利潤，而不會考慮提高價格準確性所帶來的社會利益。
A prize-winning paper from Carlos Carvalho recently showed that it does not even help if many prices adjust quickly, because those that change slowly will distort the rest. Amazon may be able to adjust its prices easily to reflect its costs, but that is little use if those costs are distorted by slow adjustments from, say, the bookbinders or the freight handlers.
卡洛斯•卡瓦略(Carlos Carvalho)最近獲獎的一篇論文表明，即便是許多商品價格進行了迅速調整，結果也無濟于事，因為變動緩慢的價格將會扭曲其它價格。亞馬遜或許能夠輕松調整圖書價格，以反映其成本，但如果圖書裝訂商或貨運商的價格調整緩慢，導致這些成本扭曲，那么，亞馬遜的做法就沒什么作用。
Coca-Cola's experience reflected exactly that: long before the introduction of vending machines, they had signed a perpetual fixed-price contract to supply their bottlers, at a time of very low inflation.
可口可樂的案例反映的正是這種情況：早在引入售貨機之前很久，該公司就在通脹非常低的時候簽署了長期的固定價格合同，向罐裝商供應可樂。
I drank a 500ml bottle of Coke while writing this article, and it cost me 85p ($1.70) from the corner shop. I'd rather have paid a nickel, but price changes are important. Perhaps I shouldn't be too ungrateful.
在撰寫本文時，我喝掉了一瓶500毫升的可樂。這是我從街角的商店以85便士（合1.70美元）的價格買的。我寧愿付的是5美分，但價格變化非常重要。或許我不應該太不知感激。
