What Is the "Achievement Index" People Are Talking About?

The State Board of Education’s Achievement Index has been the subject of several blog postings and comments, recently.  The index is a worthwhile tool and provides much needed information, though it has some odd characteristics.   It’s a complex tool and no one seems interested in telling readers about the index itself.  So, let’s take a shot at that.

According the OSPI”s website (https://eds.ospi.k12.wa.us/WAI/ ), the goals of the Index are:

•    To provide a fair and consistent measurement of Washington’s public schools.

•    To present a clear picture of how schools and districts are performing.

•    To demonstrate improvement over time and highlight closing achievement gaps.

•    To tell us more, in an easier-to-understand way, than the federal "No Child Left Behind" Act’s requirements for Adequate Yearly Progress.

•   Show how well low income and non-low income students perform.

The index has the four indicators:

•    Achievement by non-low-income students

•    Achievement by low-income students

•    Achievement compared to other schools with similar demographics

•  Improvement in student achievement

It also measures Reading, Writing, Math, Science, and Ext Grad Rate (which I take to mean Extended Graduation Rate).  It then averages those five scores.  It also creates a composite index score for each of the four indicates in each category.  So, it has a total of 30 information cells.  

The scale of measure is 1-7.  No school receives a zero, unless data is not available and the cell is left blank. 

The index scale is as follows:

Exemplary = 5.50-7.00               or a range of 1.10

Very Good = 5.00-5.49             or a range of   .50

Good = 4.00-4.99                 or a range of 1.00

Fair = 2.50-3.99                 or a range of 1.50

Struggling = 1.00-2.49            or a range of 1.50

Now, that’s a decidedly odd distribution of index values.  If you infer that “Good” is the middle, the two upper tiers consist of a range of 1.60 points and the two lower tiers consist of a range of 3.00 points.  Clearly it is weighted toward the lower end of the scale.

Also, including achievement and improvement (think of that as proficiency and growth) the indicators create a very awkward statistical anomaly.   Take Federal Way’s Thomas Jefferson High School as an example. 

Achievement of non-low income students in Reading (7) and Writing(7).  The same scores for low income students are Reading (5) and Writing (6).  In other words, both are Very Good to Exemplary.  But, because there’s little room left for improvement from those high levels, Jefferson’s Improvement scores for Reading (3) and Writing (1). 

In the process of averaging the indicators, the scale’s improvement indicator actually punishes Jefferson for having such high level achievement scores.  Another decidedly odd characteristic of the index. 

You can see examples of the index and look up your own schools here:

https://eds.ospi.k12.wa.us/WAI/IndexReport/dropdown