interesting analysis
I had one of the lower passing scores (from the 40/60/80 calculation) last year and was initially surprised when I saw that I passed based on the distribution of scoring ranges. I was also quite surprised that I had so many <70s. It was a bit of a humbling disribution.
I’m somewhat convinced (although I can never prove this and it really doesn’t matter now that I have that enormous certificate on my office wall) that my >70 scores were probably on the higher end (toward 100) and that many of my non-passing sections were still in the “almost” 45 to 65% range with a skew toward the higher end. While I did try to be familiar with all topics, and did lots of practice questions and some exams, I did find that certain sections and topics I just knew very well throughout the process and was consistently getting good marks in these areas and average in everything else.
40/60/80 is a nice rule of thumb for the broad testing population but it doesn’t explain scores for those folks who either score at the lower end of each range (thus, failing when it looks like they should have passed) and those who scored, on average, at the higher end of each range (passing, when their distribution makes them look like a fail relative to other distributions).
I think there is another explanation - perhaps the CFAI places additional topic importance weights to the marks. That is why people who gained below 65% on average if you take a blank number have passed and those gained above 65% have failed. I believe this takes place.