I saw this graph resurface at a BBC event on learning recently (by someone who had written a book on adult learning). I thought this graph had been put to bed some time ago. Clearly not.
Units of ten!
A quick glance is enough to be suspicious. Any study that produces a series of figures bang on units of ten would seem highly suspicious to someone with the most basic knowledge of statistics, and even a passing acquaintance with learning theory is enough to dismiss the comparisons outright. Learning what? Learning to read? Riding a bike? Understanding a written passage in Aristotle? Learning is a complex business. This is simplistic nonsense.
Good detective work
You can read the whole strange tale on Will Thalmheimer's site:
The lead author of the cited study, Dr. Chi of the University of Pittsburgh, a leading expert on ‘expertise’ when contacted by Thalheimer said, "I don't recognize this graph at all. So the citation is definitely wrong; since it's not my graph." What’s worse is that this image and variations of the data have been circulating in thousands of PowerPoints, articles and books since the 60s.
Further bogus additions
Further investigations of these graphs by Kinnamon ((2002). Personal communication, October 25.) found dozens of references to these numbers in reports and promotional material. Michael Molenda ( (2003). Personal communications, February and March.) did a similar job. Their investigations found that the percentages have even been modified to suit the presenter’s needs. The one here is from Bersin. Categories have even been added to make a point (e.g. that teaching is the most effective method of learning).