问题如下：
1. The inclusion of index returns prior to 2001 would be expected to:
选项：
A.bias the historical equity risk premium estimate upwards.
B.bias the historical equity risk premium estimate downwards.
C.have no effect on the historical equity risk premium estimate.
解释：
A is correct.
The backfilling of index returns using companies that have survived to the index construction date is expected to introduce a positive survivorship bias into returns.
我想问下，题干里 relatively recently established a market economy这个是什么意思，市场经济？对index有影响吗？
