Readers with long memories may recall the brief, inglorious UK fuel shortage of a few weeks ago, which was mostly caused by the rush to refuel for fear the pumps would run dry. Some petrol stations imposed a limit on how much you could buy — say, £25 of fuel and no more. It seems sensible enough, but a friend of mine (an economist) suggested this was the opposite of what was really needed. A maximum purchase encouraged more visits and more queues. Instead, petrol stations should’ve imposed a minimum purchase: nobody was allowed to buy fuel if their tank was more than a quarter full.
記性好的讀者可能記得幾周前英國經歷的短暫而不光彩的燃料短缺，它的主要原因是衆人擔心加油站會沒油，因而一窩蜂跑去加油。一些加油站對顧客可以購買的數量設置了上限，例如25英鎊的燃油。這似乎是明智的，但我的一位朋友（一位經濟學家）認爲，這與真正需要採取的做法恰恰相反。設定一個購買上限，只會鼓勵人們多次光顧加油站，加入排隊的車流。相反，加油站應該規定一個最低購買資格門檻：不允許油箱內仍有四分之一以上燃油的人購買燃料。