Pair programming and lean software development

I have learned quite a lot from reading Lean Software Engineering, a website authored by Corey Ladas. Although I am not personally acquainted with him, I have gained a great deal of respect for his thinking and his experiences in applying lean principles to software development.

My growing respect for him may be the reason I was struck by a comment of his that I came across recently while browsing the site. In a response to a reader’s comment dated January 7, 2008, he wrote: “Pair programming is antithetical to Lean” It was just a flat assertion with no explanation.

I was puzzled. Lean software development doesn’t speak to particular development practices, as far as I know. What might cause a practice to be antithetical to lean or, for that matter, to support lean? The only basis I could think of on which to reach such a conclusion was that the practice either hinders or helps us in applying lean principles to software development. Corey did not provide the same level of careful analysis and explanation as he does with most of the useful material on his site, so I decided to reason through the question myself.

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All evidence is anecdotal

It’s a commonplace for people to disparage the direct experience of practitioners and to favor the indirect observations of researchers. This has always struck me as a rather strange attitude. A person who does a thing every day, and whose livelihood depends on doing it well, surely knows what has worked and what has not worked well in practice, at least in his/her own experience. Someone who takes the work seriously will naturally remain open-minded about learning new techniques and methods throughout his/her career, building up a deep and reality-based understanding of the work over time. People working in different domains will have had different experiences and will have solved different problems, so if you listen to several experienced individuals representing different industry sectors you will end up with a pretty good cross-section of practical knowledge.

A practitioner who explains what he/she has found useful in the field is giving you an anecdotal report of his/her experience. Is a researcher giving you any better information when he/she publishes the findings of a study? Isn’t the researcher giving you, for all practical purposes, an anecdotal report of his/her experiences in preparing a research paper? Both forms of evidence are anecdotal, are they not? Would you really dismiss the opinions of a 35-year veteran of software development in favor of a report prepared by a couple of graduate students who had never written a line of code in anger, and whose main purpose in doing the study had been to learn how to “do a study?” Are the hundred-odd real-world projects the veteran has completed really less informative than the two or three sets of apples-and-oranges observations the graduate students made in their study? Anecdotal evidence is still anecdotal, even after someone publishes it. The question is whose anecdotes carry more weight.
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