The best or most compiler writers born in February?

Derek Jones from The Shape of Code

Some years ago, now, I ran a poll asking about readers’ month of birth and whether they had worked on a compiler. One hypothesis was that the best compiler writers are born in February, an alternative hypothesis is that most compiler writers are born in February.

I have finally gotten around to analyzing the data and below is the Rose diagram for the 82, out of 132 responses, compiler writers (the green arrow shows the direction and magnitude of the mean; code+data):

Rose diagram of birth month of compiler writers

At 15% of responses, February is the most common month for compiler writer birthdays. The percentage increases to 16%, if weighted by the number of births in each month.

So there you have it, the hypothesis that most compiler writers are born in February is rejected, leaving the hypothesis that the best compiler writers are born in February. How could this not be true :-)

What about the birth month of readers who are not compiler writers? While the mean direction and length are more-or-less the same, for the two populations, the Rose diagram shows that the shape of the distributions are different:

Rose diagram of birth month of non-compiler writers