Calculate the upper and lower bound in Excel using Descriptive Statistics, a part of the Analysis Toolpak that comes with Excel 2013.
Open a worksheet containing a column of data. Insert a column title if there isn't one already. Make sure there are no blank rows or columns between the data cells.
Add the Data Analysis option to Excel's Data ribbon. Click the File tab, select Options and then click Add-Ins. Select the Analysis ToolPak and click the Go button.
Click the Data tab and then the Data Analysis icon that now appears in the ribbon. Select Descriptive Statistics and click OK.
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Click the Input Range text field and then drag the cursor across the column of data, including the title. Click the Tables in First Row check box.
If you don't select the title too, the Statistics table this process creates is named after the first cell of data.
Click the Output Range text field and then click any blank cell to the right of your column of data. A two-column table will appear in this cell. Click the Summary Statistics and Confidence Level for Mean check boxes. Leave the Confidence Level for Mean at its default 95 percent value. Click OK to create the analysis table.
Adjust the column size as needed so that you can see the whole table. The Mean is in the first row, while the Confidence Level is in the last row.
Click a cell below the table to calculate the Upper Bound. Type an =, click the Mean value, then a + and then click the Confidence Level value. In this screenshot the formula is =E3+E16. Press Enter to calculate the formula.
Click another empty cell below the table to calculate the Lower Bound. Type an =, click the Mean value, then a - and then click the Confidence Level value, such as =E3-E16.
Save your workbook.