School Choice or Best Systems_ What Improves Education_ - Margaret C. Wang [32]
The data clearly show that students attending private schools score higher on standardized tests and graduate and enter college at higher rates than students attending public schools.5 For example, private schools have outstanding records for their graduates gaining admission to elite public and private universities. A 2006 survey6 of elite public and private college and university admissions offices reveals that in 2005, on average, 41 percent of the freshman enrollees attended private K-12 schools (see Table 4-2). Since the enrollment in private schools in the United States is only about 11 percent of all U.S. K-12 students, private school students are four times as likely as public school students to gain admission to elite private colleges and universities. Even if private schools did not yield superior achievement and achievement gains, it seems likely that many parents would like to have their children exposed to peer groups bound for such prestigious institutions.
Table 4-2 ENROLLMENTS OF PRIVATE HIGH SCHOOL STUDENTS IN ELITE COLLEGES AND UNIVERSITIES
SOURCE: “Enrollments of Private High School Students in Elite Colleges and Universities,” Wall Street Journal, September 15, 2006, p. W10.
College or University Percent of Private School Students among Enrolled Freshmen
Amherst College 40
Bowdoin College 46
Brown University 42
Cornell University 23
Dartmouth College 38
Duke University 37
Georgetown University 49
Middlebury College 48
Massachusetts Institute of Technology 22
Pomona College 35
Princeton University 40
Stanford University 30
Swarthmore College 35
University of California, Berkeley 86
University of Chicago 33
University of Pennsylvania 48
Yale University 46
Average 41
Private vs. Public School Achievement
But do these effects of private schools remain after controlling for family income, parents’ level of education, and other possible confounding factors? Researchers seeking answers face major obstacles. The private school sector is small and relatively heterogeneous compared to the public sector. Private schools vary greatly by size, spending level, curriculum, and student demographics, which makes it less likely that studies will yield clear, consistent results. Private and public schools in different states also use different achievement examinations, which adds to the difficulty of making comparisons. In addition, differences in family motivation and background rather than school effectiveness may cause achievement differences between the two sectors.
All of these methodological difficulties were apparent in a study released in 2006 by the U.S. Department of Education purporting to show no positive effect of private schools on academic achievement .7 In an extensive critique,8 Paul Peterson and Elena Llaudet pointed out the study’s fallacious drawing of causal inferences from single-point-in-time achievement scores; the underestimation of the prevalence of disadvantages such as poverty, limited English proficiency, and special needs in private schools; and the overestimation of these characteristics in public schools. The study also incorrectly controlled for differences in student absenteeism and the availability of books and computers in the home, which are factors that vary by school sector. These incorrect controls further biased its results.
After fixing such flaws, Peterson and Llaudet found that Catholic, Lutheran, Evangelical Protestant, and independent school fourth-and eighth-grade students all scored higher on National Assessment of Educational Progress tests in mathematics and in reading than did their public school counterparts after appropriate statistical controls were used. Peterson and Llaudet, however, were careful to avoid any firm causal inferences from single-point-in-time achievement scores from small samples.
An earlier study by John Chubb and