问题如下:
An analyst tests the profitability of a trading strategy with the null hypothesis being that the average abnormal return before trading costs equals zero. The calculated t-statistic is 2.802, with critical values of ± 2.756 at significance level α = 0.01. After considering trading costs, the strategy’s return is near zero. The results are most likely:
选项:
A.statistically but not economically significant.
B.economically but not statistically significant.
C.neither statistically nor economically significant.
解释:
A is correct.
The hypothesis is a two-tailed formulation. The t-statistic of 2.802 falls outside the critical rejection points of less than –2.756 and greater than 2.756, therefore the null hypothesis is rejected; the result is statistically significant. However, despite the statistical results, trying to profit on the strategy is not likely to be economically meaningful because the return is near zero after transaction costs
这道题我们所相信的(备择假设)是超额收益不等于0. 但这个设想本身就是在“before trading cost”的前提下的呀。后来实际验证时候,考虑到了trading cost,return才接近0(意味着如果跟最初设想时候的前提一致,即before trading cost,收益的确≠0).所以应当是经济学上有意义的呀?