I can't remember where I read it, but many DYS kids are clustered near the minimum qualification levels with only a small minority who are significantly beyond the minimums.
Statistically, this is probably true. If you cut off the tail at one end of the curve, especially way out from the middle like the DYS qualifier, the bulk of the people remaining will be close to the cut line, with relatively few further out. So, for example, if the cutoff score is 145, 68% of the population will be at or under 150 (assuming a normal distribution and a standard deviation of 15: 1-(P(Z=3.333)/P(Z=3.000)) ). I don't know exactly how the multiple ways to qualify as a DYS affect this calculation, but my "gut feeling" is that it makes the group more likely to be clustered close to the qualifier line, rather than increasing the weight of the tail. I'd be interested to hear from anyone whose statistics is less rusty than mine about whether my gut is correct or not.
