- the database at the Center for Applications of Psychological Type. They've collected thousands and thousands of Form G results submitted by practitioners all over the place, from people working in multiple fields. In a ton of those fields, ISTJ isn't considered particularly responsible. Further, in high schools, where a lot of the early sampling was done, ISTJ is definitely NOT considered the way to be...In the CAPT database, I think ESTJ is the modal type--I can't find my old manual that shows it...
- The National Representative Sample developed by the publisher of the official MBTI, CPP, Inc. When they created Form M in 1998, they performed a rigorous study using all the statistical gizmos to get as good of a sample as they could across education/income/gender/culture/career to correct for as much bias as they could. In this sample there are really 2 modal types since score ranges are shown: ISFJ and ESTJ.
I can also see evidence that a majority of people answer as they prefer, not as they think they should, when I look at results from people within specific careers--the data on how types cluster in careers is actually validity for the theory. And a lot of that data is on best-fit type: the types people select after going through training, not merely their reported scores.
The point of the instrument is to help figure out types faster so you can get on to interpretation. If I don't use the instrument with a group, I need about another 30 minutes to do some concrete exercises so people can "See" the preferences and decide which ones suit them best. If training is effective, by the end of the second day everyone appreciates the gifts of each preference, how all types contribute to a team, and why you'd only want to be yourself.