Defect Classification

As per ANSI/IEEE standard 729 the following are the five level of defect classification are

1. Critical: The defect results in the failure of the complete software system, of a subsystem, or of a software unit (program or module) with the system.

2. Major: The defect results in the failure of the complete software system of a subsystem, or of a software unit (program or module) within the system. There is no way to make the failed components, however, there are acceptable processing alternatives which will yield the desired result.

3. Average: The defect does not result in a failure, but causes the system to produce incorrect, incomplete, or inconsistent results, or the defect impairs the systems usability.

4. Minor: The defect does not cause failure, does not impair usability, and the desired processing results are easily obtained by working around the defect.

5. Cosmetic: The defect is the result of non-conformance to a standard, is  related to the aesthetics of the system, or is a request for an enhancement.  Defects at this level may be deferred or even ignored.

     In addition to the defect severity level defined above, defect priority level can be used with severity categories to determine the immediacy of repair.  A five repair priority scale has also be used in common testing practice. 

 The levels are:  

• Resolve Immediately: Further development and /or testing cannot occur until the defect has been repaired.  The system cannot be used until the repair has been effected

• Give High Attention:  The defect must be resolved as soon as possible because it is impairing development / and or testing activities.  System use will be severely affected until the defect is fixed.
• Normal Queue: The defect should be resolved in the normal course of development activities.  It can wait unit a new build or version is created. 

• Low Priority: The defect is an irritant that should be repaired but which can be repaired after more serious defect have been fixed

• Defer:  The defect repair can be put of indefinitely.  It can be resolved in a future major system revision or not resolved at all.

                                                            Total effort spent in testing

Cost of a defect              ==                ------------------------

                                                             Tot. no. of defect.

                                                            No. of Test cases

Testing efficiency                  ==        -----------------

                                                            No. of defects.

Defect Closure rate    ==                   how much time takes to close the defect

                                                            No. of defect

Defect Density             ==                  --------------

                                                             KLOC/FP        

  KLOC- Kilo Lines Of Code

  FP - Functional Point analysis.