Reference : Charts and display preferences : Radar charts
  
Radar charts
The radar chart displays the priorities for the selected view and all criteria.
When you hover the cursor over the check box of an element, the lines of that element become bold. You can show and hide criteria contributions by selecting the check boxes in the criteria list.
Example radar chart
To hide or show the lines for an element, press Alt and select the checkbox of the element. This feature is useful if your chart contains many elements and you want to study the lines of a subset of the elements.
See also
Charts and display preferences