中文摘要：

基于12家商业银行1997～2005年间的数据，对商业银行信息技术资本的边际生产率和最优投入规模的实证研究结果表明，我国商业银行信息技术资本的边际生产率是正的，且其大小受银行规模和时间的影响；四大商业银行信息技术资本的边际生产率小于中小规模商业银行；银行整体的信息技术资本边际生产率随时间呈现不断增长的趋势；四大商业银行信息技术投资已经超过了最优规模，而中小商业银行尚未达到最优规模。四大商业银行应该着重提高信息技术资本的利用率，完善互补机制，而中小商业银行应进一步加大信息技术的投资量。研究结果证明，当前“信息技术生产率悖论”在我国商业银行中并不成立。

英文摘要：

Empirical study of marginal productivity of IT capital and optimal investment size of commercial banks based on data of 12 commercial banks from 1997-2005 shows that： marginal productivity of IT capital of our commercial banks is positive and sub-ject to banking size and time; marginal productivity of IT capital of the four big commercial banks is smaller than that of small-and-medium sized banks; marginal productivity of IT capital of the whole banking sector is on the increase along with the advance of time and IT investment by the four big commercial banks has overreached the optimal size while IT investment by small-and-medi-um sized banks has not. The four big commercial banks should better utilize their IT capital and improve mutual-complementary mechanism while small-and-medium sized banks should invest more in IT. Study reveals that “IT Productivity Paradox” does not exist in our commercial banks.