# Thread: Confidence Interval Estimate Between Two Means

1. ## Confidence Interval Estimate Between Two Means

Hello all. New user, first time poster, but this looks like a community that can help me learn.

I am taking a statistics course and I am at a point where we are learning how to determine the confidence level estimate between two population means. I have not received any support from my professor (that MBA tuition hard at work for me!) and the textbook does little to help. The problem that I am trying to solve and, I hope, will flip a switch in my brain about how this works is as follows. If you happen to own the textbook, Applied Regression Analysis: A Second Course in Business and Economic Statistics - Fourth Edition, it is exercise # 35 on page # 44.

The question asks to construct a 95% confidence interval estimate of the difference between two population mean returns. The data set is provided on a disk, but I have uploaded the spreadsheet for it here. I understand that the difference between the means is 5.06 and, per the answer key, the range of 95% confidence is -4.04652,14.17225, but I can't even begin to understand how to arrive at that.

The professor referred me to a figure in the book, but it is nothing more than a MINITAB output. It doesn't help me because, for one, I'm using Excel instead of MINITAB, and second, it shows me nothing of the steps required to input values to get that result.

Is anyone able to help me simply with what inputs to use in order to arrive at the correct output? I have tried using various t-Test macros under the "Data Analysis" heading, but I can't figure out how to arrive at that range.

Any help is most appreciated. If there is other information I can provide to help find what I'm looking for, I will be happy to do so.

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