Also Iintroduce REQML estimator which has good properties in the model have many week instruments,and two moment estimator:MM and MMK estimator.

• 介绍了含有大量工具变量，且很多都比较弱的情形下性质比较好的REQML估计（随机效应拟极大似然估计），同时介绍了另外两种矩估计：MM估计，MMK估计。