Lies, Damn Lies, and Accreditation

The accreditation scores for 2016-2017, based on the 2016 testing, are up on the VDOE site.

In the distant past (2005), VDOE’s opaque accreditation process transformed 76.3 and 73.7 math scores at Jeter-Watson into “perfect scores” and embarrassed the Governor.

They now admit to the practice:

Accreditation ratings also reflect adjustments made for schools that successfully remediate students who initially fail reading or mathematics tests. Adjustments also may be made for students with limited English proficiency and for students who have recently transferred into a Virginia public school. All of these factors are taken into account in calculating pass rates in each subject area.

(But don’t ask them for the retake data.  They’ll tell you to go breathe ozone.)

The accreditation “adjustments” to pass rates are not so dramatic these days, an average of 2.25 points on the math tests this year, but they still have significant effects.

Turning to the current data, here are the distributions of math pass rates and “adjusted” rates, by school.


The green diamonds are the counts of actual math pass rates by school; the gold squares are the counts of the “adjusted” rates; the smooth curves are fitted Gaussian distributions.  The fitted mean increases from 83.2 to 85.3.

Note: The database has math accreditation scores for 45 schools that are missing from the SOL database; I have omitted those schools.  Similarly, the SOL database has math scores for eight schools that do not appear in the accreditation database.  The data here are for the 1774 schools that appear in both lists.

The plot of counts of “adjusted” minus actual rates emphasizes how the “adjustments” decrease the numbers of not-accredited scores (<70) and increase the counts of accredited scores.


Notice how the number of “Adjusted” scores decreases just below and about the 70 point cutoff and increases up in the “accredited” range.  In fact, the “adjustments” inflate the number of accredited schools from 1555 to 1653.  That boosts the percentage of schools from 87.7% to 93.2%.

NOTE: These numbers are math only; the number of schools fully accredited for all subjects and graduation rates is, of course, smaller.

VDOE writes the SOL tests.  They can boost the pass – and accreditation – rates simply by making the tests easier.  Yet they indulge in this opaque process to produce meaningless numbers.

And remember that the pass rates themselves have been fudged: See this and this.

Moreover, they do not adjust the scores for the one factor that they measure and that we know affects the rates: Economic Disadvantage.

So “opaque” is insufficient.  “Opaque and corrupt and unfair” comes closer.

Your tax dollars at “work.”