MAPC Releases Important Clarification on Report on Equity


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On October 12th the Metropolitan Area Planning Council (MAPC) released an analysis of the school assignment plans proposed by BPS. The part of the analysis that got the most attention was a comparison between the new BPS proposals and the current plan. It indicated that the new proposals might improve equity for African American and Latino students over the current three zone plan.

On October 26th, MAPC released an important clarification to their original report (you can read the original report and the clarification). This clarification points out that the comparison in the original report was not apples-to-apples. It compared the limited information we have about the new plans with actual attendance patterns under the current plan. When a more direct comparison was done it showed that the six zone plan proposed by BPS might be slightly more equitable. The other proposed plans would likely be less equitable. Unfortunately, this clarification has not received as much attention as the original reports.

All of this is still very preliminary. In order to fully evaluate any of these plans we need to be able to simulate actual attendance patterns. This will require more data from BPS and likely more time than is available under the current timeline.


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Apples to apples comparisons are a big step in the right direction.

Is Boston still using the same algorithm for matching that is described in the paper linked here?……

The issue it raises is this:

"It is costly in the Boston mechanism to list a
first-choice that you do not succeed in getting
because, once other students are assigned their
first-choice places, they cannot be displaced
even by a student with higher priority."

though students can select three schools, many
children do not get any of their picks because, if
a parent and student choose three popular
schools and do not get their first choice, they
may also miss their second and third choice."

Many parents seem to believe currently that they if they go after a hard-to-get-into school and miss, they will not fare well in getting the alternatives they'd hoped for.

Answering my own question, it seems they did change the mechanism. So parents' perceptions may just be a result of the difficulty of getting assigned to high-demand schools.

"In June 2005, the Boston school committee voted to replace the Boston mechanism with the student-optimal stable mechanism (Gale and Shapley 1962), a mechanism where participants can do no better than report their preferences truthfully."

Josh Weiss's picture

Josh Weiss's picture


Thanks for all your good comments. As the paper you linked notes, the Student Assignment Task Force that made recommendations in 2004 recommended changing the algorithm to Top Trading Cycles (TTC). In the end, the School Committee decided to implement the Gale/Shapley algorithm. This algorithm is considered "strategy proof" which means that parents do not need to consider their first choice an all-or-nothing decision but can list schools in their actual order of preference. You might have noticed that Peng Shi refers to TTC as having some possible benefits. It might be worthwhile for the EAC to consider this as part of their recommendations.

It's worth mentioning that Shapley and Roth (who was a co-author of the paper you linked) recently won the Nobel Prize in Economics for their work in this area. Also, Parag Prathak who is another co-author is currently working with Peng and BPS to try to create a model that could be used to predict the impact of these plans under real-life conditions.

So there's no reason for parents to forgo putting a popular school as a first choice. The only additional consideration is that you can only be placed on wait lists for up to three schools. So it is a good idea to put a less-popular school in your top four choices if there's a less popular school that appeals to you.

Thanks for the explanation.

If there are still issues with the algorithm, that may be part of the problem - so it would seem like they may at least want to determine whether it's something they need to look into. Obviously there's a lot the EAC needs to do, but it may be as significant as some of the other issues they are considering.

There may also be suggestions to make around implementation. (It's great that the EAC is planning to include those, and have already started trying to get implementation issues identified.) I know BPS already offers help to parents, but part of the implementation should include a really clear explanation of how the assignment process works, including the algorithm. As everyone knows, the process is daunting.

Sorry to hijack this post, but for those interested in the algorightm - a link to the 2005 BPS presentation, with some discussion and comparison of the algorithms and the choice of the Gale-Shapley approach:

I leave it to the economists to make the case - but it seems they made a lot of progress in changing the algorithm the last time and it would not be as compelling to do it again.

But again, there's some improvements that might be made in implementation.

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