Tuesday, May 22, 2018

The Devil's in the Demographics

This scatterplot shows the relationship between the percent eligible for Free or Reduced-Price Lunch within a school and the percent performing at Grade Level or Above on the 2017 KS State Assessments (Reading and Mathematics). 

We all want to be able to compare things.  Humans have a drive to qualify the world around them by determining what is better and what is worse.  The problem is, we often make these judgments without considering all the pertinent facts.

Take school performance, for example.  What if you wanted to make a Report Card that compared schools on state assessment results?  What would you need to take into consideration?

From a statistical standpoint, you would want to find all the things that can reliably predict student outcomes on these state assessments not related to school effectiveness, then you would want to somehow take these into consideration when comparing one school to another, to make sure you were really getting a sense of the differences based on the school's influence rather than on other outside factors.

KASB has spent quite a bit of time with the Kansas State Assessment data for the past few years.  We've compiled in an online tool which can be found here:

https://public.tableau.com/views/KSDE_Assessments/KSDEAssessments

In the process of examining this data, we have found several demographic characteristics at both the school and district level that are significant predictors of school performance.  In other words, we can reliably predict student outcomes on the Kansas State Assessments based on a variety of factors not directly related to school effectiveness.

Here are some examples of what we found:
  • Larger schools have lower percents of students performing at grade level.
  • Schools in districts with higher percents of white students have higher percents of students performing at grade level and at college and career ready. 
  • Schools in districts with higher percents of Hispanic students have lower percents of students performing at grade level and at college and career ready. 
  • Schools in districts with higher percents of ELL students have lower percents of students performing at grade level and at college and career ready.
  • Schools in districts with higher percents of Migrant students have lower percents of students performing at grade level and at college and career ready.
  • Schools with higher percents of Economically Disadvantaged students, which is measured by the percent of students eligible for Free or Reduced-Price Lunch, have lower percents of students performing at grade level and at college and career ready. 
  • Schools in districts with higher percents of Students with Disabilities have lower percents of students performing at grade level and at college and career ready. 

If all of the above are true, then a rating system that did not take these factors into consideration would be biased towards smaller schools with high percents of white students and low percents of students that are Hispanic, English Language Learners, Migrant, Economically Disadvantaged, and that have Disabilities.  

This is certainly something to consider when looking at any kind of rating system that claims to present an accurate comparison across schools in Kansas.  


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