Conditional Formats on Another Columns

You can create conditional formats to apply to one column based on the values of a second column, for display in tables and pivot tables. For example, you can create a conditional format to color the Region column green when values of the Sales column are greater than $30 million.

You can create a condition using a column that is not displayed in views for the analysis, if you use the Hide option on the Column Format tab of the Column Properties dialog. If you place the column in the Excluded drop target of the Layout pane, then you cannot create a condition using that column.
Conditional formatting is applied based on the underlying value, even if you select the Show Data As options in the Layout pane to show the data as percentages or indexes.