Last week, a post on Skeptics Stack Exchange tried to back up a claim put out there a couple of months ago by John Carmack (co-founder of id Software) that Stack Overflow (SO) “has probably added billions of dollars of value to the world in increased programmer productivity.” Using some back-of-the-envelope calculations, site moderator Sklivvz estimated that over the course of its five-year history, the popular question-and-answer site for programmers has added about $30 billion dollars worth of value. Based on this very quick estimate, Carmack’s claim seems to be supported.
As you might expect, this has generated quite a bit of discussion and debate all over the Internet. Many people think this estimate is way too simple. It makes some pretty big assumptions (e.g., each page view of an answered question saves a programmer 1 hour of time; each hour of time saved equals $20 of value added) and ignores some things such an analysis would ideally take into account (e.g., the cost of time spent answering questions). But, to be fair, Sklivvz is really providing this simple analysis to get the discussion going and to see if anyone can come up with a more rigorous answer.
Nevertheless, this sort of quick analysis is fun to debate. So, in the spirit of that, I decided to take it a step further and add my own quickie calculations to try and see just how much value Stack Overflow adds on a per-programming-language basis. Prepare yourself for more non-rigorous statistical analysis!
Before presenting my own methods, here are the results:
Now, my methodology:
For each of the 20 languages, I estimated the percentage of the total SO pageviews for answers to questions tagged with that language. Since I don’t have (easy) access to the actual page views per question tag, I proxied for it by multiplying the total number of page views of all questions answered by the portion of total questions answered which were tagged with that language.
Given the number of pageviews of questions answered per language, I then simply multiplied that by the valued added per pageview ($20, using the same value as Sklivvz).
Now matter how you measure it, I think we can all agree that Stack Overflow is a big help to developers. Exactly how much is probably impossible to quantify. But, again, these back-of-the-envelope approaches are fun to discuss, if nothing else - as long as we don’t spend too much time on them, taking away from more important tasks, like reading and answering questions on Stack Overflow.
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