今天看了一篇论文，有两个问题向大家请教：

用来反映证券市场月度的增长指标该用什么量来反映呢？国外的论文是这么说的：Expected economic growth is defined as the natural logarithm of the average monthly growth in the Department of Commerce Composite Index of 11 Leading Indicators from Datastream for months t,t-1and t-2。

另外，价格水平改变该怎么表示呢？国外的论文是这么说的：Equity price level change is the return of the CRSP value-weighted market portfolio over months t-5 to t.

麻烦大家帮帮忙！！