> but he doesn't count how many of them do not move at all. The whole diagonal of his (sample) transition matrix are actually missing values, but he treats them

> but he doesn't count how many of them do not move at all. The whole diagonal of his (sample) transition matrix are actually missing values, but he treats them as zeroes Great point. It's interesting to think about how exactly this could bias the results -- would it bias it in favor of languages that developers tend to initially not choose for their project? I do see that as very consistent with C, C++, and Java being up there. For new projects, developers love to choose anything but those, but then they find themselves gravitating towards them when the project gets bigger and practical concerns intrude