Public-, Private-School Test Scores Compared
The average standardized-test scores of students in suburban public schools with high academic standards approach those of students in comparable private schools and are significantly higher than those of other public-school students.
The comparative findings come from an analysis of test results from the Comprehensive Testing Program--the standardized test employed by most of the nation's independent schools.
The Educational Records Bureau, a nonprofit education organization that distributes the ctp examinations, annually makes available the normative data necessary to make comparisons of test performance in the various school environments.
A select group of public schools hold membership in the erb and administer the test routinely, along with independent schools. Test data from other public schools come from field testing by the Educational Testing Service, which developed the ctp exam to the bureau's specifications.
The erb, founded in 1927 at Teachers College, Columbia University, has more than 900 members.
Suburban public schools are elected to membership in the erb based on a number of criteria. These include a per-pupil expenditure of at least $4,000, median student test scores 15 to 25 percentile points above the national public-school medians on achievement tests, a 25-to-1 student-teacher ratio, graduation rates of at least 90 percent, and college-going rates of at least 80 percent, with at least a 45 to 50 percent rate for four-year colleges.
The ctp test was given to some 125,000 independent-school students and some 80,000 suburban public-school students last year. Test items have a greater level of difficulty than commercially prepared standardized tests, according to R. Bruce McGill, president of the erb Many commercial examinations, he said, fail to test the able and very able student adequately.
Taken by students in grades 1-10, the test includes multiple-choice achievement and aptitude questions focused on listening, reading com-prehension, word analysis, mathematics, vocabulary, the mechanics of writing, and English expression.
Mr. McGill attributed the differences in test scores mainly to differences in student bodies. "The independent-school population is selective," he said. "You therefore have a more academically competitive group."
He added that smaller class size, greater resources, and a more nurturing environment may also contribute to the higher test scores in suburban and independent schools.
What the examination tells school systems, he added, is how suburban public-school students compare with similar private-school populations. "It's a way of assessing school effectiveness," he said. "Is the school getting the kind of mileage out of the kids you would expect?"--lo