We have seen that, as expected, school division performance on the SOL is affected by the relative affluence of the students. Indeed, on the 2016 Virginia data, it appears that the percentage of economically disadvantaged students explains about 25% of the variance in the division SOL pass rates.
Excel is glad to recast the data to express the division pass rates as differences from the least squares fit. When we do that calculation for the reading subject, the graph of pass rate v. % ED
becomes a plot of (pass rate – calculated pass rate) v. % ED:
As before, Richmond is the gold square. The red diamonds are, from the left, Hampton, Newport News, and Norfolk. Charles City is the green diamond.
In this case, we see Richmond move from the lowest reading pass rate to the fifth from lowest rate after correction for the average (well, least squares fitted) influence of economic disadvantage.
Note that all four of the lower performers have much lower ED percentages, with only Petersburg breaking 50%. Among the divisions with larger ED populations, Richmond’s reading performance is uniquely awful.
Applying the same process to the math pass rates we see:
Here, only one of the high-ED divisions (Lancaster Co.) underperformed Richmond.
Finally, the five-subject averages, where we get bragging rights only as to poor Petersburg.
Please forgive me for saying it again: Economic disadvantage is a problem but it’s not the problem with our schools. That problem is lousy schools.