You can do this via a custom formula and then the correct filter in a work ticket list.  For example, the custom formula might be Gross Margin - Estimated Gross Margin as a percentage.  You might name is “Est vs Act GM”  

Then, in your work ticket list, you could add a filter for “Est vs Act GM Greater than OR Equal To 0” and the results might look as follows (This is data from our Aspire Test System): 

I would try something like…. create an advanced formula for work ticket that has Estimated Gross Margin - Gross Margin (named GM% Differs). You would then set you list filter on your work ticket page for GM% Differs less than 0. You could then also use it to look at those that are greater than 0 to see what is underperforming.  

Looking at those tickets with AGM better than estimated

                            GM% Differs Less than 0

Looking at both performance sides

                            GM% Differs less than X

                            GM% Differs greater than X

                                  Condition is 1 or 2

Set X to an acceptable differences. If being off the estimated by 5% is ok then set X to 5.

**If you want the performed better than to be the positive number...flip the equation

GrossMargin] - bEstimatedGrossMargin] Then you would set list filter to GM% Differs Greater than 0.