Our officers and soldiers in the field generally do very well against their opponents, if not encumbered by ridiculous ROE, etc. It is the upper echelons and even more so our political leadership that loses us wars.
A Category IV seems to be the %tile of 10-30. That is basically a score for the retarded.
In 1997, the ASVAB was reengineered to to allow less educated and dumber applicants to be accepted. The resulting scores were about 5% lower between the 1980 baseline and the new 1997 scorings but the armed forces could then lower the qualifications claiming recruiting levels were not met. The new 1997 test questions came with adjustments to the scoring calculations, which are a complex set of weighted stat equations and not a direct percentage scoring of right answers.
The goal of the 1997 ASVAB reengineering was to social engineer blacks and Hispanics (their own words) to pass the ASVAB. The new test questions included phrasing questions in such a way as to allow those lesser educated demographics to understand the questions. The scoring calculations were also adjusted to weight those questions differently.
The academies also suffered under this new scoring. I turned down the USAFA in 1983 because I thought the school was a second rate education. I was wrong. It was third rate. I'm not sure the academy even expels poor performing students. I know students carrying a C- GPA (and that's with grade inflation) who are not bounced out. I know professors there that wish they could flunk out students but they cannot.
If you want to know all the math and science behind the 1997 ASVAB changes from the 1980 standards, download the PDF.
