Every year D.C. announces with much fanfare the annual results of the standardized test that all D.C. public school students take, the D.C. CAS. Last year the scores were declared historic because they rose by 4 points. This year’s scores barely budged, but there was still a big press event and much discussion of whether they show education reform has been working in D.C. But how reliable are the test scores?

Here are things to bear in mind when considering the results:

Proficiency rates are decided by policy-makers. The scores that D.C. has released aren’t actual test scores but the percent of students deemed proficient. Proficiency is not an absolute. Rather, D.C. education officials pick a certain “cut score.” Students who score above that level are classified as proficient or advanced, and those below are basic or below basic.

That means that proficiency rates are essentially a matter of policy. Last year, controversy erupted when D.C. officials rejected a recommendation from teachers to use a new grading scale that would have made it harder for students to be considered proficient.

D.C. officials have said they kept the old grading scale in order to ensure that scores from prior years would be comparable, but critics have charged manipulation and called for officials to release students’ underlying scores.

Proficiency rates don’t tell you about growth. If all you’re hearing about is how many students are proficient, you don’t know how many students have moved up from one category to another. For example, students who manage to move up from below basic to basic aren’t counted.

[Continue reading Natalie Wexler’s post at Greater Greater Education.]

Natalie Wexler is the editor of Greater Greater Education and a member of the board of the D.C. Scholars Public Charter School. The Local Blog Network is a group of bloggers from around the D.C. region who have agreed to make regular contributions to All Opinions Are Local.