How have approaches to quality changed over the past 20 years?

Mary and Tom Poppendieck

We can all learn a great deal from people who have influenced our industry. BCS SIGiST recently hosted a discussion with Mary and Tom Poppendieck about “How have approaches to quality changed over the past 20 years?”. Mary Poppendieck wrote books with her husband Tom about Lean Software Development based on her experience of applying the principles of the Toyota Production System to software development. The term “lean software development” originates from their books. Adam Leon Smith chaired the discussion which lasted an hour, and here are some highlights. 

The discussion started with a conversation about what is quality, about how it relates to requirements. Mary questioned whether we should use the word integrity rather than quality. Mary and Tom spoke about their experience of how often specifications changed in manufacturing, and how often specifications change while creating products.

They spoke about how SpaceX is highly instrumented. This high level of instrumentation creates observability as the output of the instrumentation enables engineers to find the cause of test failures.

There was also a discussion about pull systems. Mary also spoke about how when she changed her factory from having a push system to having a pull system all the inventory disappeared. She also spoke about how better flow improved quality.  

Covid has meant that we need to reconsider our attitude to remote work. The focus now needs to be on outcome rather than output. Tom spoke about how Open Source projects in the 1990’s had this focus, so in that way remote is not new. In these projects people solved their own problems and took responsibility. You had to make sure that your contribution worked.

We need to make it difficult for mistakes to get into products and mosquitoes were used as a metaphor. When considering quality you need to think whether it is better to “swat all the mosquitoes in the house” or to “put up screens to keep the mosquitos out of the house”.

Tom spoke about how to get smart people to work together on complex problems. At SpaceX engineers are responsible for functions and teams include people who are good at finding problems. The whole team contributes to meeting the goal.

Tom Gilb was in the audience and asked a question about defect prevention.

I would recommend using the link below to listen to the whole discussion:

Published by Mike Harris

Mike has been working in testing for 20 years and is currently the lone tester for Geckoboard. He has been a Test Lead and has also worked as a part of waterfall, lean and agile teams. He is also Programme Secretary of BCS SIGiST. Mike has a B.Sc.(HONS) from Middlesex University and is an Associate of the University of Hertfordshire. He has set up and led a Testing Community of Practice and been part of a successful agile transition. He is Co-Programme Chair of the British Computer Society’s Specialist Interest Group in Software Testing. He also contributed to the e-book Testing Stories and has had articles published by the Ministry of Testing. Follow Mike on Twitter: @TestAndAnalysis

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