00418pab a2200157 454500008004000000100001700040245008000057260000900137300001400146362000800160650001300168650001700181700001800198700001500216773002900231180718b2009   xxu||||| |||| 00| 0 eng d  aCai, Hongbin  aObservational learning: evidence from a randomized natural field experiment  c2009  ap.864-82.  aJun  aLearning  aObservations  aFang, Hauming  aChen, Yuyu  aAmerican Economic Review