You'd be amazed how many smart people don't have a decent grounding in statistics, so any easy reference to explain this is nice.

Fair point, and yes it's quite informative from that point of view. I didn't like his approach however, he seemed to be beating around the bush a lot with phrases like

  I'm here to rescue you with a statistically sound yet incredibly simple formula

than giving a more honest 'hey, what you need is Standard Deviation, and here's how it works!'

No Torn, you're still not using the correct statistic.

THIS HAS NOTHING TO DO WITH STANDARD DEVIATION.

Also, how can you say that the article isn't "honest," especially given the complete, precise explanation for the stats at the end.

Seems I'm haemorrhaging karma over this. I misjudged the method used (Pearson's Chi Square, as pointed out by hn user pibefision). Fine, that'll teach me to skim read and comment.

My point above was that the author could have come out and labelled it as such in the article.

No, he explained Pearson's Chi Square.