How Do We Measure Absolute Quality?
One problem with implementing the proposed "home-based" student assignment plans is that BPS is currently assigning schools to tiers using quartiles. This means the top 25% of schools are in Tier 1, the next 25% in Tier 2, etc. The problem is that even if schools improve significantly, there will be four tiers with approximately equal numbers of schools. Ian pointed this out in a comment on a previous post and it has been discussed by the EAC.
One of the advantages of the home-based plans is that they can be flexible over time. If, as we all hope, quality improves significantly, families will automatically be given fewer choices because they won't need to go as far from home to get to high quality schools. But if we always have the same number of schools in each tier, we'll just be moving school choices around. We'll never get to the point where we can reduce the number of schools offered or the distance traveled.
I think that the EAC would like to set some absolute measure of quality. For example, they could say that if at least 70% of students in a school scored advanced or proficient on the MCAS, that would be a high quality school. Of course the problem with this is that there's no clear number that we can all agree is "high quality." And to try to agree on three breakpoints that would allow us to group schools into four tiers seems impossible.
One solution would be to simply use the existing four tiers and take the breakpoints from the quartiles. BPS is creating a single number for each school based on two years of MCAS scores. Let's say that in order to be in tier 1, that number has to be 60 or higher, tier 2 ranges from 52 - 59, etc. We simply set the tiers to be driven by those numbers in the future. This is still fairly arbitrary, but there's really no way to avoid that if we're going to break schools into tiers based on some kind of quality score. What it does mean is that three years from now we'll be using the same absolute measurement of what a tier 1 school is that we're using now.
Most importantly, it would mean that if many schools improve we would have far more tier 1 and 2 schools and far fewer tier 3 and 4 schools. Under the home-based plans this would result in families having fewer choices covering smaller geographic areas. The families most affected would be those who would have a lot of schools over a wide area to choose from in the first years of the plan. Those families would also see a higher percentage of their choices move into the higher tiers.