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Joel? Doing it wrong?
December 14, 2009, 6:31 am
Filed under: Uncategorized

There has been quite a lot a noise around Joel Spolsky these days. Joel is the author behind the much respected Joel On Software technical blog, and the co-founder of the now famous Stack Overflow.

The target of the recent critics (Splosky has balls of steel and a brain of feathers, Joel Inc., Stackoverflow Careers and Jumping Sharks) is mainly his new website, Careers Stack Overflow: “Stack Overflow Careers might be a bridge too far, writes William Shields.

Well. As a reader of Joel, and as a fairly successful user of Stack Overflow, I was not really paying attention to the rants. For sure, I disagree with the concept of Careers, and I dislike the way Joel uses his blog to communicate about the site. But I was thinking “heck, everyone has to make money!“.

But his last blog entry went too far.

The claim

Joel shows an interesting histogram, the ratio of Stack Overflow users that have submitted a CV to Careers, in relation to their Stack Overflow reputation:

Histogram retrieved from Joel's blog

And Joel comments:

The higher someone’s Stack Overflow reputation, the more likely they are to have submitted a CV to Stack Overflow Careers. […] it somewhat confirms the claim we’re making to employers, which is that when you search for CVs on Stack Overflow, you are looking at some pretty gosh darn good programmers.

Really? Joel, how honest are you with your readers here?

Debugging that statement

First, there is the somewhat questionable assertion that users with high reputation on Stack Overflow are “darn good programmers”. While this might be true for users with 15K+ reputation, I am not sure the rule still stands for others. And of course, I am not sure I would like to hire someone spending an important part of his work time answering over and over the same questions instead of doing what I’m paying him for. But let’s be fair here: why not. For the sake of discussion, we’ll assume that the higher one’s Stack Overflow reputation is, the more skilled he is, and the more interesting he is to Joel’s corporate clients.

Then. “The higher someone’s Stack Overflow reputation, the more likely they are to have submitted a CV to Stack Overflow Careers.“. This part is correct, according to Joel’s stats, and I won’t question it.

But the conclusion, “when you search for CVs on Stack Overflow, you are looking at some pretty gosh darn good programmers” as he puts it, is somewhat dishonest.

The relevant statistic

We want to know how good are the programmers on Careers. Or, how high is really the Stack Overflow reputation of Careers users. Well, let’s find this!

It is easy to categorize Stack Overflow users by reputation, using the /users page, a simple binary search, a pen and a paper. You can approximate Joel’s stats from his graph. Take your favorite language, a plotting library, and here is the code!

After some Inkscape prettyfication:

Repartition of Stack Overflow reputation of careers users

Of course this histogram only takes into account Careers users that are Stack Overflow users.

But it looks like when I look at a random CV, I have 40% of chances of stumbling on an user that has 1k to 2k reputation. No offense to you if you have this much rep’ on Stack Overflow, but it is quite meaningless when it comes to recruiting you.

So, pretty gosh darn good programmers? Certainly

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