You can test significance at various levels of confidence by selecting multiple columns and then right-clicking them, selecting Significance test and then the percentage level of confidence. Letters are added to the largest of a set of cells to flag significant differences, and all significant figures are highlighted.
A quick way of testing all columns at your current level of confidence (95% is the default) is to use the Quick Sig. Test item in the Table drop-down menu (or press Ctrl+T).
Conducting a significance test
Most tests are performed by comparing figures across selected columns, however, tests can be run across rows by checking the Horizontal sig. test item in the Table menu (Shortcut key Ctrl+H).
Having selected whether a horizontal or vertical test is to be performed:
Select the columns (or rows) that contain the data you wish to test
Right click the selection to reveal a pop-up menu
Select Sig. Test, then the confidence level you wish to use (there are five options: 80%, 90%, 95%, 99% and 99.9%)
U-Tab performs a significance test and adds the results to the table.
Each column (or row) is given an identification letter and significantly different cells are highlighted in bold. Beside each bold value it places one or more letters that indicate the column (or row) that contains the value to which the highlighted cell is significantly higher.
Conducting a 'quick' significance test
If you are examining a number of tables and wish to conduct significance tests on each, there is a quick way of doing so provided you want to use the same confidence level for each test.
Select Table|Quick Sig. Test (Shortcut key Ctrl+T)