A "t table" is also known as the "Student's t Table." A critical value is the value that a test value must be greater than to reject the null hypothesis. The critical value can be looked up manually in a t-table distribution. However, it would be relatively quicker to simply use the Data Analysis toolpack in Microsoft Excel. Simply enter the data in Excel and launch the Data Analysis tool. After filling in the range details, hypothesized mean and alpha value, the results will be displayed in the output cell that was selected.
Enter data in two columns with the results. For example, a company chooses a sample of ten regions and wants to compare sales before and after a new product has been introduced. The sales data before the product launch would be entered in cells A2 through A11 and the after sales data would be entered in cells B2 through B11. Place the appropriate headings in cells A1 and B1.
Go to the "Data" tab and click on "Data Analysis" under the "Analysis" section. Select "t-Test: Paired Two Sample for Means" and click "OK." See the Tips section on how to add the Data Analysis toolpack if it is not already in the toolbar.
Enter "$A$1:$A$11" in the "Variable 1 Range" field and "$B$1:$B$11" for "Variable 2 Range." Put "0" for the "Hypothesized Mean Difference." Check off "Labels" to indicate that there are column headings in cells A1 and B1. Enter "0.5" for the "Alpha," which is the degrees of freedom.
Select "Output Range" and enter the cell number where you would like the results to be displayed, such as $A$14. Click "OK."
Locate the critical one-tail and critical two-tail t values. In our example, the values are located in cells A25 and A27.
If the Data Analysis toolpack does not appear in the toolbar, click on the "Office" button. Click on the "Excel Options" button and select "Add-Ins." Select "Excel Add-ins" in the "Manage" drop-down menu and click on the "Go" button. Check off "Analysis ToolPak" and click "OK."