Violating the Denominator Law

Sean Corcoran, who is guest blogging for the blogger formerly known as Eduwonkette, may have to go to education research jail because he violated the Denominator Law today.  For those of you unfamiliar with the Denominator Law from my previous post on the topic (and ignorance of the law is no excuse) it is: “No one should be allowed to highlight numerators without also presenting denominators.  That is, it is often misleading to describe a big number without putting that number in perspective.”

So, Sean is all worried about private donations to public schools creating or exacerbating inequities in funding.  He references a report about California (and it had better be peer-reviewed or the blogger formerly known as Eduwonkette will throw a fit) that finds: “contributions to California school foundations rose from $123 million in 1992 to $238 million in 2001.”  He does helpfully add that $238 million only amounts to $40 per pupil.  But he doesn’t fully comply with the Denominator Law because he fails to point out that $238 million only represents .4% of the $52.2 billion in total public school revenue in California in 2001.

It’s not the average amount of private giving in California that really worries him.  What concerns him is that these donations are concentrated in wealthy areas: “Of course—as Brunner and Imazeki point out—these contributions are far from evenly distributed. Donations are strongly related to family income, and in some cases they are quite high, at more than $250 to $500 per student. (You can read about the $3.3 million education foundation in Santa Monica-Malibu Unified School District here).”

Here, your honor, is where he flagrantly breaks the Denominator Law.  He suggests that $250 to $300 per pupil, as illustrated by $3.3 million in private giving to public schools in Santa Monica, is “quite high.”  Without a denominator, it’s hard to judge how high $3.3 million in Santa Monica really is. 

Let me help.  According to the School Matters web site operated by Standard and Poor’s, Santa Monica has 12,191 students.  The private contributions Corcoran mentions amount to $271 per pupil — within his $250 to $300 range.  But total revenue for Santa Monica public schools amounted to $11,062 per pupil as of 2006.  Private contributions of $271 amount to only 2.4% of total revenue — not exactly “quite high.”

And this private giving hardly accounts for resource differences between Santa Monica and the average district in California.  According to School Matters the average district in CA had total revenue of $9,553 as of 2006, $1,509 less than in Santa Monica.  If Santa Monica received $271 in private donations compared to $40 for the average California district, the extra $231 could only account for about 15% of the extra resources Santa Monica possesses. 

If this is the worst case that folks can muster, it hardly seems like private giving is a significant contributor to resource inequities.  We only gain this appropriate perspective when we comply with the Denominator Law — so be sure to follow the law out there.

4 Responses to Violating the Denominator Law

  1. Collin Hitt says:

    I guess those wealthy benefactors should have never given at all: things in CA would be more equal, Jay Greene wouldn’t have had to spend his time writing the post above, and Sean Corcoran would have saved a little face.

  2. pm says:

    Seems to me that knowing the trends would be a lot more interesting than knowing the current state of affairs. Have foundation donations peaked? Are they just starting to accelerate? From the data reported I can’t tell if the doubling in donations between 1992 and 2001 occurred in the first two years, last two years, or steadily throughout. If an accelerating trend can be combined with some changes in the law, then maybe there is a de-facto voucher system on the horizon.

  3. I’m glad you raised the question of trends, pm, because it also shows how important obeying the Denominator Law is. It’s true that private giving, according to Brunner and Imazeki’s report rose from $123 million to $238 million in CA between between 1992 and 2001. But it is also the case that total revenue for public schools in CA increased from $28 billion to $52.2 billion during the same period.

    If we follow the Denominator Law and divide $123 million in private giving in 1992 by the $28 billion in total revenue in the same year, we find that private giving constituted .4% of the total in 1992 — exactly the same as its share in 2001. In other words, there is no rising trend in private giving relative to total school revenue.

    Be sure to add the denominator. It’s not just a good idea. It’s the law. : )

  4. pm says:

    Sure, the denominator law matters. But it seems you’ve chosen the wrong one in your comment, although I think you chose the correct one in your blog post when you explained Santa Monica spending. That’s the 2.4% figure. Given foundation contributions are constant relative to some other data point over time, it leads one to believe the trend is linear. I’d still like to see more than two data points, I guess I’ll have to search the web to find those.

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