问题如下：
1. According to the statistical results of linear regression, which of the following conclusions can Frank get?
选项：
A.the dummy variable has no statistical significance.
B.biotechnology industry PEs are statistically significantly larger than medical equipmentindustry PEs.
C.biotechnology industry PEs are statistically significantly larger than medical equipment industry PEs, holding DPO, G, and B constant.
D.medical equipment PEs are statistically significantly larger than biotechnology industry PEs, holding DPO, G, and B constant.
解释：
C is correct.
考点：Dummy Variables
解析：在其他变量保持不变的前提下，当哑变量IND=1时，意味着选取的是生物科技行业股；当哑变量IND=0时，意味着选取的是医疗设备行业股。又因为IND前的系数为正，所以生物科技行业股的P/E Ratio会比医疗设备行业股显著更高。
老师好，这道题C选项的答案解释，为什么是看虚拟变量IND前面系数的正负，而不是看t-statistic？ 与经典题无答案版本第33页第3.3题的A答案对比，经典题里看的是t statstic (p-value)。
