Interesting method but the author seems a little surprised that doing market research actually works. His sample size compared to the population seems just a liiiiittle bit too small to yield meaningful results from though and there's no real indicator of its reliability.

What would really be interesting is a long running series of these with larger sample sizes. Might cost a bit but you could probably come up with a reasonable hypothesis test and some solid results.

Fair play to him if it's not just a fluke.