1. Error Tracking Defect removal efficiency DRE = E / (E+D)
E – errors found before shipment
D – errors found during operation
Provides strong indication of the effectiveness of the quality assurance activities
Track errors in work products (requirement specifications, design documents, source code etc) to assess the status of a project
Collect error related metrics over many projects

2. Recap

3. Software Engineering II
Lecture 26
Fakhar Lodhi

4. Using Error Tracking to assess progress
Let us assume that we have collected errors and defect data over the last 24 months
Errors per requirement specification page – Ereq
Error per component – design level – Edesign
Errors per component – code level – Ecode
DRE – requirement analysis
DRE – architectural design
DRE – coding

5. Using Error Tracking to assess progress
Record the number of errors found during each SE step
Calculate current values for Ereq, Edesign, and Ecode
Compare to averages of past projects
If the current results vary more than 20% from average, there may be cause for concern and there is certainly cause for investigation

6. Example Ereq for the current project = 2.1
Organizational average = 3.6

7. Can also be used to better target review and/or testing resources
120 components
32 exhibit Edesign > 1.2 average
Adjust code review resources accordingly

8. Software Quality Software quality is defined as:
Conformance to explicitly stated functional and non-functional requirements, explicitly documented development standards, and implicit characteristics that are expected of all professionally developed software.

9. Software Quality 3 important points
Software requirements are the foundation from which quality is measured. Lack of conformance is lack of quality
Specified standards define a set of development criteria that guide the manner in which software is engineered. If the criteria are not followed, lack of quality will almost surely result.
A set of implicit requirements often goes unmentioned (ease of use, good maintainability etc.)

10. Quality Assurance
Goal is to provide the management with the necessary data to be informed about product quality
Consists of auditing and reporting functions of management
If data provided through QA identifies problems, the management deploys the necessary resources to fix it