As a CMMI Consultant, during CMMI consulting assignment, you may be asked about the benefits of CMMI related to Defects Density. CMMI Consultants may answer this question by taking input from the post below:

CMMI FAQ 0

26th November, 2014

A study was conducted by the SEI (now CMMI Institute) on the metrics data collected from 35 large organizations across the world. These organizations having low as well as high maturity apply CMMI Process Improvement practices to their Software Engineering, System Engineering and other Engineering activities.

In this study Industrial Systems Group (ISG) of Hitachi observed the effect of the peer review and quality assurance on the Defect Densities. Results are based on the pilot and statistical analysis.

Regression Analysis and Statistical Process Control were used for Quantitative Project Management. Initially ISG observed that there was a strong negative correlation (r2=.72) between defect detection prior to unit testing and total defect density throughout the product life cycle.

Based on the study it was observed that:

• Total defects in projects were lower if defects were found initially in the project.
• Effort and Cost of fixing the defects found in the UT (Unit Testing) was 2.28 times more than the defects found in the peer review.
• That Peer Reviews based on the Process Improvement were more effective than pre-process improvement phase.
• That there was an improvement in the Productivity, Cost and Product Quality due to improvements in the Peer Reviews.
• Fagan-style inspections were giving better results than less formal reviews and there were 4.5 to over 10 times more defects found with these inspections. It also leads to the cost saving due to less expensive defects closure of defects found in earlier inspections.
• With respect to the review best practices, it was found that the it helps if we identify in advance the work product to be checked, controlling the duration and number of participants in reviews. These findings were then implemented in the other pilot projects.
• Further in big projects, when doing only single review for the project leads to escaping of more defects during peer reviews.

As seen here, Peer Review With and Without Tool Aid, there was an increase in the upper limit of manageable review size by 30 percent and ROI (Return on Investment) for Fagan Inspection was 3.9:1 and for less formal walkthroughs ROI was 2.3:1. Data from 16 pilot projects was collected and out of these defects density of 15 pilot projects was found to be lower than defect density baselines established by ISG. The ROI of 1.7:1 was also observed due to the decrease in the cost of testing and reviews. QA Department also observed a ROI ratio in the range of 6.3:1 to 9.8:1 attributed to the costs of correcting field errors and other management and engineering problems, factored into the ROI ratios.

This shows that CMMI Process Implementation can lead to improved reviews, less number of defects and reduced cost of fixing defects with the implementation of process improvements.

Source: Performance Results of CMMI®-Based Process Improvement Report.