I know, it's a bit of a dog-bites-man headline, but bear with me. A new study by a Rutgers University ed. professor purports to tell us about "Private Schooling in the U.S.: Expenditures, Supply, and Policy Implications." The trouble is, the study presents no data that are representative of private schooling in the U.S.
Author and ed school professor Bruce Baker analyzed per pupil expenditures of private schools that had registered with Guidestar.org. Based on its mission statement, Guidestar is a service brings together charities seeking donations with would-be donors, in an effort to encourage philanthropy. Only a fraction of the nation’s private schools participate, and they are self-selected into that group. It is reasonable to think that the schools that self-select into Guidestar are the ones most avidly seeking donations. According to a PowerPoint presentation on Guidestar's site, its top five types of users are:
- Non-Profit Development Directors
- Non-Profit Fundraising Directors
- Grant Writers
- Foundation Grants Administrators and Donor Services Managers
- Corporate Foundation Giving Program Managers
Quite possibly, the private schools most actively seeking non-tuition revenue are the ones... receiving the most non-tuition revenue. So not only is the Guidestar population of private schools not randomly selected, and non-representative of private schools nationally, there is reason to believe it is biased in the direction that its author and funders favor.
This would be bad enough, but it gets worse. The author makes no serious attempt to determine the extent of the bias, or to control for it. In fact, he consciously makes it worse: he choses to eliminate from consideration any private schools reporting revenues or expenditures under $500,000, thereby excluding smaller, less expensive schools.
I have literally NEVER seen a serious academic study that starts from a sample that is known to be biased in the direction favored by its funders and then consciously makes matters worse by actively skewing it even further!
An example of the kind of analysis that is supposed to accompany the presentation of a non-random sample to ascertain extent and direction of bias appears in my own 2006 study of Arizona private schools, available here. I dedicate five pages (beginning on page 14) to an assessment of whether and to what extent my survey respondents differed from the universe of all Arizona private schools. Significant effort was expended on that section of the study, because it is both necessary and expected. I was disappointed, though not surprised, by the absence of such a section in the Baker study.
Not only can the Baker study not tell you how much U.S. private schools really spend, it seems to have a little difficulty getting the public school spending figures right, too. For instance, there is a line on page 42 implying that DC public schools were spending $14,000 in 2007. Federally-reported data show that DC was already spending over $18,000 per pupil in 2005-06. And I've shown that it spent $28,000/pupil in 2008-09.
Finally, did I mention that Baker's study was funded by the NEA-bankrolled "Great Lakes Center for Education Research and Practice"? As Ed Sector pointed out a couple of years ago: "The Great Lakes Center and the NEA's Michigan affiliate are also linked on a personal level: [the Center's director] Teri Battaglieri is married to Michigan Education Association Executive Director Lou Battaglieri."
Update: Note that the reason Guidestar only has financial information for a small fraction of the nation’s private schools is that the vast majority of U.S. private schools are religious, and religious schools are not required to file IRS Form 990 (from which Guidestar gets its financial data). The religious private schools that do file Form 990 are thus a small self-selected group that is presumably seeking to maximize its revenue from charitable donations, and hence very likely biased toward higher spending schools.