单选题

Using the following sample results drawn as 25 paired observations from their underlying istributions, test whether the mean returns of the two portfolios differ from each other at the 1% evel of statistical significance. Assume the underlying distributions of returns for each portfolio are normal and that their population variances are not known.

A、 accepted because the computed test statistic exceeds 2.807.
B、 rejected because the computed test statistic exceeds 2.807.
C、 accepted because the computed test statistic is less than 2.807.

【正确答案】 B

【答案解析】

The test statistic is:hereis the mean differenceμd0 is the hypothesized difference in the means, sd is the sample standard deviation of differences, and n is the sample size. In this case, the test statistic equals: