Cohort Reporting

Cohort Reporting is a Necessity

Most schools and school districts report the summative data by grade for the year, and may sometimes report the previous year’s data as a comparison. Unfortunately, this does not provide an accurate picture of student performance in the district. The problem of incomplete or non-comparative data is due to:

  1. The data are not the same student group and differences in the groups’ pre-performance from year to year may cause variations.
  2. Percent proficiency scores vary across grades, so that a grade 4 group may actually do better than their grade 3 performance, but the percent proficient declines.
  3. The inability of the district’s data system to track students’ performance across time as a cohort.

To solve this problem, three changes in the way data are stored and coded are necessary.


First, student scores cannot be stored in separate files, one for each year of testing.

Second, student scores need to be transformed into a common scale which will make them comparable across time. Percentile ranks are not the answer, instead all percentile rank scores need to be transformed to normal curve equivalent (NCE) scores, while keeping the percentile rank scores in the data file. Third, a kindergarten entry date or a first date of testing in grade 3 added to the data file is necessary for ease in writing queries for reports. So for each year the student scores are uploaded into a data system the same student ID number has the same K_ENTRY date. Therefore, a chart of the data would look like this:

The Report 

School 000 is a school with an increasing number of students achieving proficiency and a very high NCE Difference EVAAS Gain. Whereas, the 001 school has a small drop in proficiency, not enough to raise concerns, however the school also has a declining EVAAS Gain Score for both RD and MA for grade 5.

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