10x reduction in post release defects – Finest experience of applying STEM

This is about one of the finest experiences that STAG had with a global chip major where the early implementation of STEM yielded significant results. Our engagement with them was to setup an effective validation practice for their porting level API for video decoders. The customer had a great technical team and were involved in both development and QA. The challenge that they faced with their complex product that involved both hardware and software and later system integration on multiple real time OS on various platforms, was that of high defect escapes i.e. post-release field defects.

We spent about a month understanding their domain and the associated technologies. Post this, a detailed analysis yielded interesting data – test cases were primarily conformance oriented, coverage of test cases was suspect, escaped defects seem to propagate from early stages and finally the process of validation was loose.

Having understood the types of defects that were being found and the post-release defects, we figured out the various types of probable defects and the various combinatorial aspects that need to be considered to form a test case. We then staged the validation as consisting of three major levels, the first one at API level, then the next one at a system level, and the last level made up of a customer-centric level that involved using reference applications.

Applying the STEM approach to test design, the test cases were developed, yielding about 6000 test cases at level one and about 800 at the subsequent levels. Also, whereas the ratio of +ve vs –ve test cases was earlier towards the +ve side, after our re-design, the ratio shifted to 60%:40% at the lower level and about 85% :15% at the higher levels. Moreover, the test cases increased in number significantly by a factor of 1000%, allowing for a larger and deeper net to catch many more serious defects. Over the next 9 months, the rate and number of defects detected increased dramatically, resulting in post-release issues reducing by a jaw-dropping 10x times.

Once we solved the test effectiveness problem and increased the yield of defects, the focus shifted to streamlining the process by setting up proper gating in the test process and creating a centralized web based test repository, and finally setting a strong defect analysis system based on Orthogonal Defect Classification (ODC) method. This enabled a strong feedback system, resulting in shifting the defect finding process to earlier stages of SDLC and thereby lowering cycle time. Complementing this, we focused on setting up a custom tooling framework for automating this non-UI based software resulting in a significant cycle time reduction – an entire cycle of tests on a platform took less than 15 hours of time!

This has been one of the finest experiences that we had with STEM, and was a clear winner for STEM implementation. This was only possible because of the very mature engineering management staff of the customer, who were focused on systemic improvement and had systematic improvement goals.

What is to be noted is that our test team was NOT a team with significant depth of experience on the particular product domain. Applying STEM at a personal level, the team was able to understand what was necessary and sufficient for effective validation and complemented the strong technical team with mature defect-oriented thinking. This was an early case study for us to establish that a STEM based approach provided us with the right thinking skills for defect finding, rather than resort to a domain centric approach to defect finding.

“The quality race” – STEM wins

A large German major with a mature QA practice is seeking new ways to improve its test practice. It all starts with a talk delivered at this company on “The Science & Engineering of Effective Testing” to its senior management staff and test practitioners in the company. We are amazed at the interest in this topic (75+ people attend the talk) and the enthusiastic response – we are deeply humbled.

A few weeks after this, the management decides to experiment with STEM-based approach to testing. They identify about twenty five people (a small subset of their QA team) to be trained on the new way of testing. We are delighted and conduct a 5-day workshop with intense application orientation, to enable them to understand STEM. The company then decides to conduct a bold experiment- a pilot to evaluate STEM powered approach to testing vis-a-vis their way of testing. They identify a product that is in use for a few years with consumers across the world. They decide to have two five-member identical teams consisting of similar mix of experience levels of people, each given a timeframe of one month to evaluate the new release of this product. These two teams are kept apart to ensure a controlled experiment and the countdown starts. We wait with bated breath…

The month is slow for us, but it flies for the two teams. Enormous data has been generated and the management analyses them thoroughly to spot the winner. A month later we are called by the senior management. We are sweating, have we won? A few minutes later, it is clear that STEM is a winner. The STEM powered team has designed 3x test cases compared to the non-STEM team and uncovered 2x number of defects! The icing on the cake is that the couple of defects uncovered by the STEM powered team are “residual defects” i.e. they have been latent in the product for over a year (Remember Minesweeper game on Windows) and one of them corrupts the entire data in the database. Now the discussion steers to effort/time analysis – Does application of STEM require more effort/time? The team has conclusive evidence that it is not significant, implying STEM has enabled them to think better, not work longer or more.

What enabled the STEM powered team to win the “Race of quality” ? The answers are given by the team itself, and we are delighted, as we have believed in them, and have seen results when we implement them. The top three reasons are: (1) The notion of Potential Defect Types (PDT) is powerful as it forces the team to hypothesize what can go wrong and enable them to setup a purposeful quality goal (2) PDT forces a thorough understanding of the customer expectations and the intended behavior of the product (3) PDT ensures that test design creates adequate test cases, thus eliminating defect escapes and paving the way for robust software.

The STAG team is delighted as their customer acknowledges the effectiveness of the STEM based approach. The team is convinced that STEM powered approach is a winner and is raring to run the marathon, with the customer also cheering them to win!

A heartfelt “Thank you” to the STEM powered team and the innovation-centered Senior Management of the company.