经济增长因素总结

Gene M.Grossman and Elhanan Helpman (1994) survey the recent literature on thedeterminants of economic growth and divide these works into three types: oneset considers the accumulation of “broad” capital, including human capital anddifferent types of physical capital. A second set of papers utilizes spilloversor external economies, and finally a third set “casts industrial innovation asthe engine of growth”.

还可以看Aghion and Howitt （2009）著作里面总结的三类模型。

基础设施的作用

Telecommunicationinfrastructure investment can lead to economic growth in several ways. Mostobviously, investing in telecommunications infrastructure does itself lead to growth.

As the telephonesystem improves, the transaction costs fall, and output will increase. Telecommunicationinvestments might lead to benefits in other sectors. In other words,telecommunications investments have important spillovers and createexternalities.

内生性问题之反向因果

Reversecausality implies that one needs to distinguish two effects: (i) the increasein economic growth, which is attributable to increases in telecommunicationsinfrastructure and services development; and (ii) the increase in the demandfor telecommunication services, which is attributable to increase in economicgrowth (i.e. the income elasticity of telecommunication demand). The causationis clearly two-way and, unless telecommunications infrastructure investment ismodeled, the measured effect on telecommunications infrastructure on growth willbe biased. In this paper we attempt to estimate a simultaneous model fortelecommunication investment and economic growth. We specify a structuralmodel, which endogenizes telecommunication investment by specifying amicromodel of supply and demand for telecommunication investments. The micromodelis then jointly estimated with the macro production equation. In this way, weendogenize telecommunication investment, controlling for the simultaneouslydiscussed earlier.

评议：从文章学到什么？

1.这是一篇好文章，字里行间折射的是作者广博的知识。比如，作者对经济增长因素的总结寥寥数语，足够清晰。再比如对通讯设施的特性的把握，给文章增色不少。

2. 文章的写法，对结果的分析方法，循序渐进，值得学习。

3. 作者分析了通讯基础设施与经济增长之间的门槛效应。门槛是一个范围而且是非线性，使用Dummy进行门槛分析，具有优越性。

如果非要说不足的话，作者对PEN这个变量划分为高、中、低三档时，dummy的划分依据需要进一步阐释。因为这影响着后面结果的分析。