the slides from the talk are here:
http://www.slideshare.net/gvwilson/bits-of-evidence-2338367
(see slide 20)
I realized today I got it from somewhere else..
(Facts and fallacies of Software engineering)
Looking up the whole reference in that book gave me the title,
and googling that gave me the the paper
http://drum.lib.umd.edu/bitstream/1903/703/2/CS-TR-3424.pdf