Here are two graphs that I made concerning the correlation, or lack thereof, between general indicators of poverty and student achievement.
One is from DC public elementary schools, and one is from DC charter schools.
I used the NCLB-OSSE data to look up the numbers of students deemed ‘economically disadvantaged’ at each regular DC public school, and then the total population tested at that school. From that I calculated the percent of students in poverty. I got the percent of students ‘passing’ in reading on the DC-CAS for 2010 simply by adding the percentages of students scoring in the ‘proficient’ or ‘advanced’ categories. I then plotted the poverty rate versus the passing rate, and commanded Excel to draw a line of best fit.
The overall trend is that the higher the percentage you have of poor students, in general, the lower the achievement scores, with a R-squared value of 0.6555. But the correlation is nowhere near as strong as what we saw with the data from DC as a whole BY WARD. Furthermore, it seems to me as if the elementary schools in DCPS are really split into two categories: the ones with very few kids on free or reduced-price lunch (that is, the 13 or so schools with less than 45% poverty rates) on the one hand, and the 70 or so schools with over 60% poverty rates on the other hand.
In fact, we have 57 schools (about 68% of the total number of schools) in DCPS with poverty rates greater than 80%. These are the ones that fill the two right-hand blocks on the graph. Only a small handful of those very-high-poverty schools have ‘pass’ rates that are greater than 50%.
I will list the 13 DC public schools with low poverty rates, and I bet that many of my readers could guess the names of most of them. Here is the list, which represents about 15% of all regular DC public elementary schools. Next to each school is the percentage of students in poverty.
My next exhibit is a similar graph for the forty or so DC public elementary CHARTER schools.
As you can see, the correlation between poverty and achievement is not nearly as strong in the charter schools as it is in the regular public schools. In other words, the dots don’t all cluster so tightly around the line of best fit, and the R-squared value is much lower, namely, 0.1646. Furthermore, there is not nearly the same clustering of high-poverty schools as we see in the regular DC schools. If you recall, DC public elementary schools overwhelmingly had greater than 80% poverty rates, and almost none between 40% and 60% poverty rates. Not so the charter schools, of which I count a total of 42. I see a relatively small group of schools with low poverty rates, which I will list:
Childrens Studio School 9%
Achievement Preparatory Academy 11%
NIA Community 20%
Ideal Academy Pcs – North Capitol Street Campus 23%
Latin American Montessori Bilingual 30%
Two Rivers – Elementary 30%
Community Academy Pcs – Online Program 30%
That group represents about 19% of all DC elementary charter schools.
The intermediate group, which has between 40 and 60% poverty rates, consists of nine schools (21% of the entire group – as opposed to a single, solitary DC public school). There are 26 charter schools (62% of the total) which have greater than 60% poverty rates. And there are only 16 public scharter schools (38% of the total) which have greater than 80% poverty rates.
So this graph appears to confirm what I suspected (and wrote) earlier: middle-income students seem to be deserting the regular public schools and flocking to the charter schools. A lot of the very poorest students are remaining behind in the most impoverished public schools.
OK, how about achievement, as measured by the DC-CAS? (Not that I think it’s a very good test, but it’s all we have to go on.)
Well, in the regular public schools, we see that there are 20 schools (about 24% of the total number of schools) which have greater than 50% ‘passing’ rates in reading. In the charter schools, there are 12 schools (about 29% of the total) which have greater than 50% ‘passing’ rates in reading.
Extremely alert readers may wonder where the scores for Sharpe Health, St. Coletta, the Hamilton Center, and the Mamie D. Lee school are located. I felt sufficiently skeptical about those scores not to include them at all.
My first version of this column had a graph that alleged to be data from Nebraska public school districts. It fit a line of negative correlation so well that it was just as scary as the graph produced by Allan Assarsson and his son. I attempted to check the data by looking up at least a handful of the achievement scores for the Nebraska school districts; the data I found all agreed with the data I was given. However, I kinda wondered if the entire state of Nebraska really only had twenty (20) school districts. That number seemed a little low (not that I know a lot about Nebraska), and the data seemed to fit the line too well.
Today I decided to look up a list of Nebraska school districts. It turns out that there are over 270 school districts in that state. Granted, a whole lot of them are districts that have less than 100,000 total population (not students, but all men, women, and children together). Not knowing where to find the necessary data on all 270 of those school districts, and not knowing if the author of the table had simply taken a true random sample of the districts, or had merely cherry-picked the ones that best fit his or her prior opinions, I decided to eliminate the graph and table all together.