Some time ago I became aware that the <sign> matrix in the very first lesson in my teacher resource book has a flaw in it!
For years I worked with the assumption that there was an <-ify> suffix in words like <signify>. I then was presented with evidence that showed that this was an incomplete analysis.
In May 2013 I made the most recent revisions to my book to address my new understanding. (Other changes were minimal, and not corrections of understanding -- just of typos and clarity.)
I've finally made time to explain my new understanding on a pdf that includes the page with revised <sign> lesson for anyone with the old copy of my book!
I use this pdf to explain the crucial difference between a "false analysis" and an "incomplete analysis" and how word sums and matrices resist the former but can accept the later.
We know we are in a healthy scientific community when our understanding continues to deepen, and we get to celebrate the flaws in our previous understandings.
Download the pdf with the new lesson and more on this topic here.