3 ms·

Out of curiousity, how many subjects would you say are necessary to start being statistically valid?

• jaggederest 10y ago
  Kind of the wrong question. It's more about qualitative sample selection and the expected effect size than it is the number of subjects. Based on my admittedly poor understanding, I would expect to see a sample size of around 70 to have the power to detect a small effect in a single-tailed T test. I would also expect to have the samples selected and balanced carefully, preferably from the target group (i.e. experienced professional programmers in the language at hand) From what I can tell, for an effect to be detected at least 80% of the time in a sample of 20 people, you'd need the effect to be >60%. I would definitely not expect that a short term project would show 60% improvement when employing similar levels of testing, changing only either before or after writing the code under test.
  • jacquesm 10y ago
    Especially not because the major benefit of TDD hits much later in the cycle, during refactoring a large chunk of code or when doing some major surgery on the whole project (and let's hope the tests are at the interface level).
• deleted 10y ago
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