真假牛顿苹果树？

经无聊者的考证，那棵激发牛顿万有引力灵感的苹果树，有史以来最有名的苹果树，不是以讹传讹的剑桥大学三一学院门口的那棵，也不是剑桥大学Botanic花园里的那棵（这棵其实只是其种子发育而成的后代），其原本正宗是牛顿在林肯郡老家门口的这棵（见下图）。其著名的《力学原理》就是在这里完成的。英国朋友曾经对我举了好几个理由说林肯是个好地方，恰好林肯郡离我住的地方不远，准备酝酿下找个时间去牛顿老宅看看。如果有幸的话希望能从那树上摘一个苹果吃吃。但是，据我无聊的推测，也许这种叫做Flower of Kent品种的苹果并不会太好吃——不然的话苹果可能先掉进牛顿的肚子里而不是砸到他头上了。

New JEP Issue

JEP, Vol.24, No.2, Spring 2010.

Some of the topics (and titles themselves) are really attractive and seem insightful to those empirical researchers. Empirical approaches, much misused and even abused these days, indeed need these fundamental thinking. It would never be exaggerated to say that we need to make  much more efforts  in our research design than in running the regressions!!

I especially like these key featured papers:

The Credibility Revolution in Empirical Economics: How Better Research Design Is Taking the Con out of Econometrics (pp. 3-30)
Joshua D. Angrist and Jörn-Steffen Pischke

Tantalus on the Road to Asymptopia (pp. 31-46)
Edward E. Leamer

A Structural Perspective on the Experimentalist School (pp. 47-58)
Michael P. Keane

But Economics Is Not an Experimental Science (pp. 59-68)
Christopher A. Sims

Taking the Dogma out of Econometrics: Structural Modeling and Credible Inference (pp. 69-82)
Aviv Nevo and Michael D. Whinston

The Other Transformation in Econometric Practice: Robust Tools for Inference (pp. 83-94)
James H. Stock