As a further look at the effect of expenditures on performance, here are the 2015 division average reading pass rates v. the 2015 division average budgeted teacher salaries (the actual 2015 salary data won’t be available until around the first of the year). Data for Accomack are missing for lack of a report to VDOE.
Richmond is the gold square; the blue circle is the statewide division average.
The fitted curve suggests that an additional $10,000 average salary is associated with a 2% increase in the pass rate but the R2 tells us that the two variables are essentially uncorrelated.
The math data paint a similar picture.
Of course, we know that increasing economic disadvantage of the student population is associated with lower pass rates. We can account for the average effect by using the correlation between pass rate and economic disadvantage to normalize the pass rates, i.e., express the pass rates as percentages of the economic disadvantage trendline rates. That produces these graphs:
Again, only minuscule correlations. And the fitted curves, to the extent they mean anything, say “no benefit from the higher salaries.”
So it seems that the divisions that pay their teachers more do not get better SOL performance; they merely pay more for the performance they get.
Finally, here for two of my faithful readers (maybe the only two) are the last two graphs showing the results for Charles City (purple circle) and Lynchburg (red circle).
Data are posted here.