In addition to the caveats they list, there may be systematic biases as to who includes a profile pic and who doesn't. Even an enormous sample and perfect inferences from the face API can't surmount a bad dataset (bad depending on what you are trying to learn from it)
Not quite. That relates to sample sizes and, as far as interpretation goes, it's dealt with as if the rest were missing at random. In reality, they are probably missing not at random, but in relation to other characteristics, changing the interpretation.
Not at all. That's just the median age, and I think the profession tends to have a lot of young people due to the size of the field at the time people chose their careers.
Even better, looks like there are a few programmers (CPP and HTML) >60 years old, though the graph shows n=0 for those data points, so do those guys actually exist? If so, the oldest programmer is 86.4, now that's impressive.
http://www.computerhistory.org/fellowawards/_media/img/fello...
http://kazimirmajorinc.com/Documents/Why-Dijkstra-didnt-like...
The old guys wrote the best stuff:
https://cr.yp.to/bib/1995/wirth.pdf