Paired T test. Tests the hypothesis that the mean difference between corresponding elements of before and after is testMean. Alternatives are Alt.less, meaning the that the true mean difference (beforei - afteri) is less than testMean, Alt.greater, meaning the true mean difference is greater than testMean, and Alt.twoSided, meaning the true mean difference is not equal to testMean.
before and after must be input ranges with elements implicitly convertible to double and must have the same length.
A ConfInt containing the T statistic, the P-value, and the boundaries of the confidence interval for the mean difference between corresponding elements of sample1 and sample2 at the specified level.