Redistricting - Jimrtex, Alternate Process, Scoring System

[muon2]

This is another Muon2 map from 2013.



Region 1 (UP and Northern LP) and Region 5 (Flint) are just outside the 0.5% tolerances.

I'm not sure I follow how you get these shifts. If populations are equalized between regions with shifts, then shouldn't the Detroit are shift out slightly more than 1.8% to the other two regions (2.0%) leaving all three slightly over population?

Are the choices of shifts set by algorithm or by the plan submitter. When this was drawn I imagined that the user submitted the shifts. Now it seems that there is an algorithm applied to get the shifts.

That leads to an important question in this process. If there is an algorithm to get the shifts, then the shifts must be taken one at a time (assuming a coded binary operation). If it is an iterative minimization process then there must be a metric to measure whether a shift is used or not. Either way the order of the shifts matters.

For example, a natural choice is to start with region with the greatest deviation and the neighbor with the greatest deviation in the other direction. In this case it would be Detroit to Bay, but Bay can't accommodate all of Detroit's excess, so how much should it shift? If it shifts just what Bay needs (since its the smaller deviation), then does 0.95% go from Detroit to Ann Arbor which would equalize those populations after the first shift? At that point, does the excess from Flint go to Lansing because it has the greatest deviation in the other direction? If the process starts from the direction of the smallest disallowed deviation, then it would seem that 0.1% would shift from Grand Rapids to the UP region. In any simple algorithm based on adjacency I find it hard to get the 0.5% from Flint to jump across to UP - more likely is a 0.2% shift from Flint to Bay and a 0.4% shift from Bay to UP.

Can you describe your algorithm for shifts in discrete steps?

[muon2]

So you are spreading the extra 0.3% in the non-compliant regions over all 10 districts. Links imply pairwise adjustments, but you use a globally determined correction. It works mathematically, but the graph isn't really needed to apply it in the way it would be if the adjustments were calculated on a pairwise basis. The only use for the graph is to determine if there are adjacent districts that are both in deficit or surplus implying that there is an extra shift to pass through population.

[muon2]

So you are spreading the extra 0.3% in the non-compliant regions over all 10 districts. Links imply pairwise adjustments, but you use a globally determined correction. It works mathematically, but the graph isn't really needed to apply it in the way it would be if the adjustments were calculated on a pairwise basis. The only use for the graph is to determine if there are adjacent districts that are both in deficit or surplus implying that there is an extra shift to pass through population.

In this case that is true, because all non-compliant regions were placed in a single area.  The effect of doing so will be to better equalize equality among all districts.  Hopefully this will produce plans with pretty good final equality, but without as much splitting up of counties.

This is where I'm confused again. It looks like you are suggesting that that the shifts are actually what will be put in the plan. I thought the shifts were just a scoring tool for submitted plans. If they are just for scoring, then the actual shifts will be different from the calculated shifts. If the system imposes certain shifts between regions, we are back to the problem of scoring actual plans for the state that are submitted.

A scoring system has to be able to evaluate a plan for all the districts in the state. For instance it should be able to evaluate the one enacted into law. Otherwise it is a process to produce a plan, not a scoring system to evaluate plans.

[muon2]

So you are spreading the extra 0.3% in the non-compliant regions over all 10 districts. Links imply pairwise adjustments, but you use a globally determined correction. It works mathematically, but the graph isn't really needed to apply it in the way it would be if the adjustments were calculated on a pairwise basis. The only use for the graph is to determine if there are adjacent districts that are both in deficit or surplus implying that there is an extra shift to pass through population.

In this case that is true, because all non-compliant regions were placed in a single area.  The effect of doing so will be to better equalize equality among all districts.  Hopefully this will produce plans with pretty good final equality, but without as much splitting up of counties.

This is where I'm confused again. It looks like you are suggesting that that the shifts are actually what will be put in the plan. I thought the shifts were just a scoring tool for submitted plans. If they are just for scoring, then the actual shifts will be different from the calculated shifts. If the system imposes certain shifts between regions, we are back to the problem of scoring actual plans for the state that are submitted.

A scoring system has to be able to evaluate a plan for all the districts in the state. For instance it should be able to evaluate the one enacted into law. Otherwise it is a process to produce a plan, not a scoring system to evaluate plans.

The shifts are what will be placed in a Stage 1 Plan, and is what they will be evaluated on.  The actual placement of the adjustment will come in Stage 2.  The shifts identified in Stage 1 will be used as targets for Stage 2 - and can be used to choose among alternatives.

For example, your plan would set a shift of 5,822 from Region 8 (Detroit) to Region (7) Ann Arbor.  The actual transfer could come from Livingston, Oakland, or Wayne counties in to Washtenaw County.

When I scored the Torie and train plans, I removed their county fragments, but used them to identify the placement of inter-regional shifts.  The size of the inter-regional shifts was calculated on the whole-county region populations.  They will be similar to, but not identical to the size of the county fragments in the plan.

I don't see why the scoring system has to be able score the final plan enacted into law.

A scoring system should be able to take any submitted plan and either evaluate it with a score or scores or reject it as failing a specific rule of construction. A standard point of reference is to compare submitted plans to the one enacted into law.