The 2006 Illinois Standards Achievement Test results include a pupil's "national percentile rank" for reading and math. In addition, 4th and 7th graders who took the state science test received a national ranking in that subject.
A national percentile ranking of 50 is average. A higher number is above average; a lower number is below average. Top-performing pupils should see rankings much higher than 50.
About two-thirds of Illinois students received rankings above 50 in reading, math and science, according to a Tribune analysis. Chicago Public Schools students fared worse, with between 42 and 54 percent of students getting rankings above 50.
About 2.3 million pupils take the Stanford test annually. The rankings are based on a sampling that includes urban, suburban and rural children across all regions.
John Wick, a testing expert and adviser to the Illinois State Board of Education, said a child getting a national ranking above 80 would expect to get into honors courses in high school.
In some of the most affluent districts, it's typical for nearly all pupils to have rankings of 85 or higher, he said.
Parents should look closely at the national ranking compared to their child's performance on the ISAT test overall, he said. If there appears to be a disconnect--such as a child getting the highest "exceeds standards" score on the ISAT but a low national percentile ranking--parents should go over their child's scores closely with teachers.