Defect Removable Efficiency (DRE)

The Defect Removable Efficiency (DRE) is the percentage of defects that have been removed during an activity, computed with the equation below:
DRE = (Number of Defects Removed / Number of Defects at Start of Process) * 100

The DRE can also be computed for each software development activity and plotted on a bar graph to show the relative defect removal efficiencies for each activity. Or, the DRE may be computed for a specific task or technique (e.g. design inspection, code walkthrough, unit test, 6 month operation, etc.)

We can also calculate DRE as:

DRE = A / (A+B)

where A = Defects by raised by testing team and B = Defects raised by customer

If dre <=0.8 then good product otherwise not.