Reposted from Jersey Jazzman’s Blog:
“This is as quick and dirty as they come, but it makes the point. Every dot here is a school in Pennsylvania. The x-axis shows how many kids taking the state’s reading test are in economic disadvantage, as measured by qualifying for free/reduced price lunch. The y-axis shows how many test takers scored “below basic,” meaning, out of PA’s four test proficiency levels, these students scored at the bottom.
Once again, note how economic disadvantage correlates to test score outcomes. Were I to do a simple linear regression here, 60 percent of the variation in this test-based outcome could be explained by student economic disadvantage.
I did a quadratic trend line to get things a little tighter (no, it doesn’t matter, and you’re a geek…). Then I highlighted all the schools in York, charters and publics. Big surprise: everyone is pretty much where you’d expect them to be. The elementary schools do a little better than prediction; the secondaries do a little worse. And the charters are right where we’d expect.”