GUEST BLOGGER: Mary Anne Mather, Using Data Senior Facilitator & Social Media Liaison on Twitter & FaceBook

If you want to tap one of the most powerful uses of data, disaggregate! Disaggregation means looking at how specific subgroups perform. Typically, formal student achievement data come “aggregated,” reported for the population as a whole—the whole state, school, grade level, or class. Disaggregating can bring to light critical problems and issues that might otherwise remain invisible.

For example, one district’s state test data indicated that eighth-grade math scores steadily improved over three years. When the data team disaggregated those data, they discovered that boys’ scores improved, while girls’ scores actually declined.different colored stick figures sorted into color-coordinated groups Another school noticed increased enrollment in their after-school science club. However, disaggregated data indicated that minority students, even those in more advanced classes, weren’t signing up. These are just some of the questions that disaggregated data can help answer:

• Is there an achievement gap among different demographic groups? Is it getting bigger or smaller?

• Are minority or female students enrolling in higher-level mathematics and science courses at the same rate as other students?

• Are poor or minority students over-represented in special education or under-represented in gifted and talented programs?

• Are students at certain grade levels doing better in core subjects?

• Are students whose teachers participate in ongoing professional development

in their content areas doing better than students whose teachers do not?

• Are the school’s most recent curriculum and instruction adjustments improving the performance of students in the lowest quartile?

To answer these or other questions, carefully consider what disaggregated data is already available and what additional data is needed. chart with bulleted list of possible ways to disaggregate dataDevelop a data collection plan that includes a wide variety of data. Consider state and local performance assessments, samples of student work, enrollment in advanced courses, participation in special programs, participation in professional development, student and teacher survey results, and more. All these can and should be disaggregated.

Some tips to help you get started with disaggregating test data:

• Thoroughly understand your school’s demographics in order to select the most relevant variables for disaggregation. NOTE: Some schools benefit from disaggregating data within demographic groups, such as Hispanic students born in the continental U.S. compared to those who are foreign born.

• Request state and district test data reports that are disaggregated relevant to your student population.

• Explore technology tools that will help collect, analyze, and report disaggregated data more easily.

• Note relevant demographic data as you collect other information about student learning.

• Ask for support from district data experts or the companies that provide your data system.  Let them know the types of disaggregated reports that will best serve your needs.

• Get your hands dirty—dive into the data using the four-phase data-driven dialogue process described in our previous tips (

What Lawrence Lezotte and Barbara Jacoby noted in 1992 in their publication, Sustainable School Reform, still rings true today, “Disaggregation is a practical, hands-on process that allows a school’s faculty to answer the two critical questions: ‘Effective at what? Effective for whom?’ It is not a problem-solving but a problem-finding process.”

* Segments excerpted from Love, N. Using Date/Getting Results: A Practical Guide for School Improvement in Mathematics and Science. (2002). Christopher-Gordon Publishers, Inc., p.39-42.