請問什麼是裙擺理論？

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裙擺理論（Hemline Theory），也稱為裙長理論或短裙理論，由美國賓州大學經濟學家喬治·泰勒首次提出。他認為：“經濟增長時，女人會穿短裙，因為她們要炫耀里面的長絲襪；當經濟不景氣時，女人買不起絲襪，只好把裙邊放長，來掩飾沒有穿長絲襪的窘迫。”“裙擺理論”認為女人會因為經濟的變化而影響其選擇裙子的款式，通過研究女人裙裝款式的變化，就可以看出當時的經濟形勢。 
“裙擺理論”作為時尚經濟學最重要的理論之一，至今仍然或多或少影響著時尚界對流行趨勢的判斷。當然，現在長裙和迷你裙同時在流行，各種彰顯個性的裙裝出現在大街小巷，僅僅通過裙子的款式已經很難看出經濟形勢。
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裙擺指數（Hemline Index）更通俗的名字叫做“牛市與裸露的大腿”，發明人是美國人艾拉‧考伯雷。女性裙擺越長，股市就越低迷；相反，女性的裙子越短，資本市場則越出現昂揚的牛市趨勢。根據這個指數，如果投資者仔細留意本年度女性裙子的長度，那就基本能準確判斷本年度資本市場的牛熊走向。這個理論把股市描述得有點像個流氓，不過說真的，在很長一段時間裏這種對應關係還真存在。
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George Taylor， an economist in the United States， made up the phrase "hemline theory" in the 1920s. The phrase is derived from the idea that hemlines on skirts are shorter or longer depending on the economy.
The hemline theory states that when the economy is strong， hemlines are short， and when the economy is tanking， hemlines are long.
Explanation
Taylor believed that when the economy was strong， women wore their skirts shorter because they were able to display their silk stockings. On the flip side， when the economy was bad， they could not afford decent stockings， so they would hide their legs behind longer skirts.
Skepticism
According to Barron's Handbook， a popular financial reference guide， the hemline theory -- "despite its sometimes uncanny way of being prophetic ... has remained more in the area of wishful thinking than serious market analysis."
History
Hemlines fell during the Great Depression， and during periods of economic strength such as the 1920s， 1960s and 1980s， hemlines got shorter.
Recession
During the recession of 2008-2009， the hemline theory did not hold up because skirts and shorts flourished， and the economy was in the tank.
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