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Apples and Oranges: Comparing Private and Public School Test Scores

Ever wished you could compare private and public schools somehow? Perhaps with test score data?

By Marian Wilde , GreatSchools Staff

Unfortunately, comparing private to public school test scores is a bit like comparing apples to oranges.

Public schools use their own stable of standardized tests, which they use for a variety of purposes: assessment and diagnostics, to name two. Private schools use a different set of tests - some derived from the same basic tests public schools use and created by the same companies - but still different enough that they can't be compared side by side with public school tests.

Public schools are required by law to administer the test chosen by the state government and to publish their test scores. Meanwhile, private schools are free to pick their own standardized tests and, because they don't rely on public funds, do not have to release their scores, though interested parents can ask to see them.

A parent in research mode cannot even compare public schools across state lines because of the wide variety of tests in use nationwide. In order to do that, all public schools would have to administer the same exam. Currently, only schools in a given state do that.

For better or worse, standardized testing seems to be here to stay. The question now is how to use test score data wisely. With that goal in mind, a handful of education researchers and school officials are working to achieve greater transparency and accountability for all types of schools.

One Way to Compare: NAEP

Several recent large-scale studies have compared private schools to charter and regular public schools using the one common test taken by selected samples of students around the country.

That test is the National Assessment of Educational Progress (NAEP), otherwise known as the Nation's Report Card. Administered by the U.S. Department of Education, the NAEP is given to students in grades 4, 8 and 12 in both private and public schools.

One of these studies, conducted by Christopher and Sarah Theule Lubienski, a husband-and-wife team at the University of Illinois, compared more than 340,000 students using math scores from the 2003 NAEP. The study found that after adjusting for socioeconomic factors, there is little difference between private and public school scores. According to the researchers, "Demographic differences between students in public and private schools more than account for the relatively high raw scores of private schools. Indeed, after controlling for these differences, the presumably advantageous 'private school effect' disappears, and even reverses in most cases."

Similarly, another study - Comparing Private Schools and Public Schools Using Hierarchical Linear Modeling - used the 2003 NEAP data. It found that after adjusting for student characteristics such as gender, race, ethnicity, disability status and English-language proficiency and for school characteristics such as size, location and the makeup of the student body, the fourth-grade reading test scores were virtually the same for private and public schools, although the math scores for public schools were higher. In eighth grade, private school students performed better in reading, but there was virtually no difference in math.

Why Most Private Schools Don't Publish Test Scores

Public schools are required by state and federal regulations to publish their test scores, but private schools - operating without public funds and outside of close government supervision - are not obligated to do so.

Just as in the public school arena, the private school community debates how much emphasis to place on test scores. Many private schools pride themselves on providing creative and nurturing environments rather than a one-size-fits-all education. Patrick F. Bassett, president of the National Association of Independent Schools, writes on the NAIS Web site that, "those who understand curriculum and instruction, and who are rightfully skeptical about the value of standardized tests in general, also worry very much about the deleterious impact of the movement on children. With all the memorization and test preparation, will students still be taught to think critically? Will they learn to love learning?"

Others argue that private schools should report how well they are doing to the community. Henry Tyson, superintendent of St. Marcus Lutheran School in Milwaukee, believes that publishing private school scores will help parents make informed decisions when choosing schools. "The reality is that there is very little accessible, useful information that parents can use," says Tyson. "The critical problem right now is that thousands of parents [in Milwaukee] are choosing very bad schools for lack of good information."

Comments from readers

"SAT scores are published by the College Board. There is a breakdown section where it delineates Public, Religiously Affiliated and Independent Schools. So yes, they are published. And as for the matter of public records or "report cards" for public schools, they are required to submit to the taxpayers what the taxpayers money is being used for and the degree at which they are successful. It is the same principle that tells us the president or our congressmen's salary they are obliged to. I do not know of many doctors who would publish what they make as a matter of public record there is no reason. As with private schools, it is only to their constituency that they are responsible to answer. Otherwise (like with the doctor) they can take their business elsewhere. And someone posted about not having a good education at private or public schools, it is not incumbent upon anyone to "fill you up with knowledge" it is the teacher's job to facilitate learning not to fill an! empty head. The student has to do the work. A consistent adherence to discipline is what is needed for a student to succeed not to sit there like a sponge. Disregarding all euphemisms, the brain in not a sponge in that crude sense of the word. "
"How can you place a objective number to "adjust" the score for gender, race, how many books in the home, days absent, etc. A score is a score; it doesn't matter what race or gender; a test doesn't know any different. I believe that we make way too many excuses for our children. "
"So let me get this right. You take the scores, 'adjust' for socioeconomic factors, and then they're even. Amazing. Take the score, and find enough excuses to adjust for and say its all the same. excellent preparation for the world. All those people in some lesser socioeconomic status complaining about opportunity or salary discrimination in the real world should take this model, adjust for socioeconomic factors and discover that an immigrant ditch digger actually makes as much money as a blue blood surgeon, once the socioeconomic adjustments are taken into consideration."
"I too agree that this article has yet to prove any point. I have experienced all schools myself and now as a parent, I am going through it all over again. I would never put money into a private school because of my experiences. Public or Private or Homeschooled, the comparison can't be done because of the one varying factor---the teachers. You could be a parent that thinks its okay to teach your kids about scifi all day, or you could be a teacher in a 5-figure per sem. school who thinks its okay to compare every subject to Dr. Who, either way you come up with mush for brains. "
"private schools especially the religious schools have very few discipline problems which if compared to ms schools would be very astonishing.... schools need to follow the students after graduation and then do comparisions to me there is no comparisions... the clothes they were and the way they appear in public is another thing that should be looked at... I as a grandparent now think it is revolting... no displicine and letting them appear and do as they like in school and in public should be very eye opening....."
"Marian, Thank you very much for this comprehensive, well-researched article. I'm not sure many parents were aware of this. I myself ran into this a few years back when looking into schools for my kids. Again, very much appreciated. "
"I can't really find any helpful info in this article. It's a waste of time to read it. I only understood that author's pointe is that private schools are bad. Author probably just envy and/or don't have money to deal with good private schools. 98% of public schools are don't have a good ratings,because not only score results ,but attention of principal and teachers,involvment,not offerings of AP and college prep classes e.t.c ,so look,it's obvious that private schools are much better with scores and everything else which I said above.Everybody knows it,so quit compare apples and oranges,it's more like apples and sunflower's seeds."
"As an educator of nearly 20 years, I can clearly see that this study was very obviously flawed, and possibly even racist? The only very obvious difference I can see is that standardized testing should take into account the different theories of origins being taught and perhaps adjust their questions accordingly? To say that 'in some cases private schools even do worse' is just ridiculous. At a college level I have seen who fares better clearly it is the students who were sent to private prep schools."
"There is no dout that there is many different ways public and private schools are different! But, I live in Southaven, Ms. and I can tell you not all private schools are equal and most of the public schools here are better than our private schools. I would not waste my money! As far as liberal teachers should be teaching your kids at home what is right or wrong. I have no dout that homeschooled kids make out better in the long run as far as education goes, but what about socially? You have to put your kids out in the real world as they grown up, and they will not be prepared for what is coming their way. Public, private, doesn't matter if your not doing your job as a parent!"
"It seems to me that a major factor was missing. The fact that public schools teach ALL children and private schools can select who they want as students is also a factor. Simply stating socioeconomic factors were considered is not at all the same thing. Public schools must teach everyone living within their boundaries. Private schools can deny admission to a student who requires more than a low student: teacher ratio."
"My three children (3rd grade, 8th grade and 12th grade) all go to Private Catholic Schools. Our schools are happy to share the standardized test scores with anyone who asks. They are displayed each year by the main door. My 12th grader was just offered a full tuition scholarship at a Michigan Public University based on her GPA, ACT and the stellar reputation of her Private Catholic School. Compare ACT or SAT raw scores then tell us what you get. In Southeastern Michigan I'll guarantee the Private Schools will be far higher. You can mess with those numbers all you want. Go out and talk to College recruiters and find out how THEY determine who is the better applicant. Stop trying to slant things to show the Public Schools in a better light than they deserve. Let facts speak for themselves. Whether its due to poverty, racial factors, powerful teacher's unions, poor parenting, call it whatever you want. Private Schools set out to deliver a rigorous academic enviroment and they more often then not suceed. Accept it and model it for the public schools. No more excuses, stop whining, results please!"
"What about FCAT? My child has attended private schools till 6th grade. Now, he is in a charter school and getting ready for FCATs. What should we expect? Any suggestions on how to prepare for them? Thank you, Worried Parent"
"I completely disagree with the author. My kids attend a private school in Bellevue Washington. We are surrounded by 3 public school districts with average or higher than average socio-economically advantaged students, as well as 2 districts who are not. We, along with all the public schools in our area and state, take standardized tests yearly -the SAT and the WASL, and we always publish our scores. There is an advantage, as our test scores prove, even over the well-off public school districts. Not everyone fits into the little box this author has drawn, and the graduates from our school (PreSchool-8th grade) who I know personally have excelled in Public and Private High Schools in our area. Having been a product of a Private K-8 education myself, and then entering into public school as a 9th grader back in the 1970's, even back then we were way ahead. Beyond the grades, kids also need to learn self-control & respect, qualities that are also stressed and expected when peopl! e are paying above and beyond for a private education. Signed, glad we are in a private school situation."
"I feel that your article gave Private schools a bad rap. I am on the school board of a private school that is K-8. We are currently working on getting our scores published and have no desire to 'hide' them as you say in your article. What I feel was not addressed is that our children are not taught the test that they take. The kids are given the test in the middle of their regular curriculum. The public schools in our area stop what they are teaching a couple weeks before the test and actually teach the test to the kids so that the information is fresh in their minds. Therefore leading to test scores that may not necessarily be accurate. We also find that the kids from our private school perform very well in high school and about 96% go on to college. "
"Reading is easy to access. Math is easy to access. Home schoolers beat Public School kids to the point of humiliating embarrassment. Home schoolers are minus all the dirt, filth, trash, together with the hidious liberal teachers who are for the most part in need of therapy....... 1st graders taught, indoctrinated, and brain washed to think that living as a Queer is good. I know what I'm talking about, I have taught in public schools. Who the hell do you think you are fooling......"