问题如下图:
选项:
A.
B.
C.
解释:
statistic上和economic上的前提(一个是扣除cost之前,一个是扣除cost以后)都不一样啊,得出来结果不一致,很正常吧?前提不一致,算出来的结果怎么能互相对比呢?如果两个前提假设都是扣除成本以后的数值,结果是不是会一致了?
星星_品职助教 · 2019年09月24日
同学你好,
这道题和这个考点并不是考察用两种方式都去做检验然后对比结果的。而是想说明:在统计学意义上的显著(不为0),可能不一定在经济学上显著。即从统计学角度来看有意义的事,可能却没有实际经济意义。
具体而言,这道题通过统计学做假设检验的方式说明了这个策略的平均超额收益不为0,所以这个策略从统计学角度上来讲是可以用的,能赚到超额收益(average abnormal return的意思即为平均来看,这个策略能给投资者带来超额收益)。
但是如果从实际经济学意义的角度来看,一个策略不能只看本身是否能赚到钱,而是还要扣除交易成本和税费。但扣完了这些后平均超额收益就几乎是0了,所以这个策略从经济学的角度来看是没有意义的。
所以这就是统计学角度不扣除成本,但经济学角度扣成本的原因。
这个不是一个重点考点,其实想说明的就是:有时候从统计学上看这件事可以做,但是在实际中真做了的话却可能却没有(经济学意义上的)好处,理解到这个程度就可以了,加油
NO.PZ2017092702000132问题如下analyst tests the profitability of a trang strategy with the null hypothesis being ththe average abnormreturn before trang costs equals zero. The calculatet-statistic is 2.802, with criticvalues of ± 2.756 significanlevel α = 0.01. After consiring trang costs, the strategy’s return is nezero. The results are most likely:A.statistically but not economically significant. B.economically but not statistically significant. C.neither statistically nor economically significant. A is correct.The hypothesis is a two-taileformulation. The t-statistic of 2.802 falls outsi the criticrejection points of less th–2.756 angreater th2.756, therefore the null hypothesis is rejecte the result is statistically significant. However, spite the statisticresults, trying to profit on the strategy is not likely to economically meaningful because the return is nezero after transaction costs本题的|test statistics|>|criticvalue|,即2.802>2.756。所以检验的结果是拒绝strategy's return=0的原假设,此时就是statistically significant。“After consiring trang costs, the strategy’s return is nezero”,说明从经济意义上是不值得去做这个策略的,即not economically significant。 Economic s是否显著是怎么判断的呢?还需要带入统计假设里面去看是拒绝H0吗?
NO.PZ2017092702000132问题如下analyst tests the profitability of a trang strategy with the null hypothesis being ththe average abnormreturn before trang costs equals zero. The calculatet-statistic is 2.802, with criticvalues of ± 2.756 significanlevel α = 0.01. After consiring trang costs, the strategy’s return is nezero. The results are most likely:A.statistically but not economically significant. B.economically but not statistically significant. C.neither statistically nor economically significant. A is correct.The hypothesis is a two-taileformulation. The t-statistic of 2.802 falls outsi the criticrejection points of less th–2.756 angreater th2.756, therefore the null hypothesis is rejecte the result is statistically significant. However, spite the statisticresults, trying to profit on the strategy is not likely to economically meaningful because the return is nezero after transaction costs本题的|test statistics|>|criticvalue|,即2.802>2.756。所以检验的结果是拒绝strategy's return=0的原假设,此时就是statistically significant。“After consiring trang costs, the strategy’s return is nezero”,说明从经济意义上是不值得去做这个策略的,即not economically significant。 为啥拒绝原假设 就是统计显著
NO.PZ2017092702000132 问题如下 analyst tests the profitability of a trang strategy with the null hypothesis being ththe average abnormreturn before trang costs equals zero. The calculatet-statistic is 2.802, with criticvalues of ± 2.756 significanlevel α = 0.01. After consiring trang costs, the strategy’s return is nezero. The results are most likely: A.statistically but not economically significant. B.economically but not statistically significant. C.neither statistically nor economically significant. A is correct.The hypothesis is a two-taileformulation. The t-statistic of 2.802 falls outsi the criticrejection points of less th–2.756 angreater th2.756, therefore the null hypothesis is rejecte the result is statistically significant. However, spite the statisticresults, trying to profit on the strategy is not likely to economically meaningful because the return is nezero after transaction costs本题的|test statistics|>|criticvalue|,即2.802>2.756。所以检验的结果是拒绝strategy's return=0的原假设,此时就是statistically significant。“After consiring trang costs, the strategy’s return is nezero”,说明从经济意义上是不值得去做这个策略的,即not economically significant。 拒绝原假设为什么要选A啊
NO.PZ2017092702000132问题如下analyst tests the profitability of a trang strategy with the null hypothesis being ththe average abnormreturn before trang costs equals zero. The calculatet-statistic is 2.802, with criticvalues of ± 2.756 significanlevel α = 0.01. After consiring trang costs, the strategy’s return is nezero. The results are most likely:A.statistically but not economically significant. B.economically but not statistically significant. C.neither statistically nor economically significant. A is correct.The hypothesis is a two-taileformulation. The t-statistic of 2.802 falls outsi the criticrejection points of less th–2.756 angreater th2.756, therefore the null hypothesis is rejecte the result is statistically significant. However, spite the statisticresults, trying to profit on the strategy is not likely to economically meaningful because the return is nezero after transaction costs本题的|test statistics|>|criticvalue|,即2.802>2.756。所以检验的结果是拒绝strategy's return=0的原假设,此时就是statistically significant。“After consiring trang costs, the strategy’s return is nezero”,说明从经济意义上是不值得去做这个策略的,即not economically significant。 老师这句话的意思不应该是Ha:u=0吗
NO.PZ2017092702000132 问题如下 analyst tests the profitability of a trang strategy with the null hypothesis being ththe average abnormreturn before trang costs equals zero. The calculatet-statistic is 2.802, with criticvalues of ± 2.756 significanlevel α = 0.01. After consiring trang costs, the strategy’s return is nezero. The results are most likely: A.statistically but not economically significant. B.economically but not statistically significant. C.neither statistically nor economically significant. A is correct.The hypothesis is a two-taileformulation. The t-statistic of 2.802 falls outsi the criticrejection points of less th–2.756 angreater th2.756, therefore the null hypothesis is rejecte the result is statistically significant. However, spite the statisticresults, trying to profit on the strategy is not likely to economically meaningful because the return is nezero after transaction costs本题的|test statistics|>|criticvalue|,即2.802>2.756。所以检验的结果是拒绝strategy's return=0的原假设,此时就是statistically significant。“After consiring trang costs, the strategy’s return is nezero”,说明从经济意义上是不值得去做这个策略的,即not economically significant。 看不懂,不应该是拒绝原假设吗?