The Defense Contract Management Agency (DCMA) 14-Point Assessment is a set of metrics used to evaluate the quality of a project schedule to ensure that the schedule is fit for purpose. And one of the 14 metrics is the Baseline Execution Index (BEI) which is an indication of how a schedule is performing against a set baseline and the video below explains how to set-up a Microsoft Project schedule to display BEI.
Addendum
If you are having errors in your BEI calculation where a summary only contains subtasks that are milestones or all subtasks start dates (current and baseline) are in the future, modify the BEI formula as shown below (changes are highlighted in bold).
IIf([Summary] AND [x = No. of Completed Tasks] <> 0 AND [y = Not 100% & BF <= Status Date] <> 0, [x = No. of Completed Tasks] /([x = No. of Completed Tasks] +[y = Not 100% & BF <= Status Date] ), 0)