Are bond returns in the period from 1972-2015 different from bond returns from 1928-1971?

Devise null and alternative hypotheses that address this statement.

Compute mean return, standard deviation, standard error, and t-statistic for each 44 year sample. Extend your analysis to determine whether the mean return for each sample is significantly different from zero at the 5% level. Provide a brief intuitive explanation for your conclusion regarding statistical significance.

In this example, there is no particular reason for calculating the vector of differences. (Which years should be paired up?) So, use the TTEST function in Excel to calculate the p-value. Assume the variances for the two samples are different. (This is a more conservative test.) Use the TINV function to back out the t-statistic for the test. Can you reject the null hypothesis at the 5% level? Provide a brief explanation of your answer to this question.

Returns on Stocks and Bonds, 1928-2015 0.6000 0.4000 0.2000 1 0.0000 0.2000 -0.4000 0.6000