Tuesday, August 3, 2010

How to read the Minnesota Legislative hPVI Chart

I've had a couple requests to further explain the Minnesota Legislative hPVI Chart I posted on Monday, so here goes.

Here is one district in isolation:



Going left to right, the first cell is blue with an 8 in it. The 8 means that this cell represents Senate district 8, the blue represents the fact that this seat is held by a DFLer. The next two cells, A and B, represent house districts 8A and 8B and the blue, again, represents that these two seats are held by DFLers. In the first three columns the color coding will either be solid blue or solid red, a district cannot be partially held by a DFLer or GOPer so there is not any shading of these cells.

Moving on to the fourth cell from the left, this is where we get into the hPVI information. The heading "SD" means that this cell represents the Senate district of the row, which is 8. The 8 in the first cell means that this entire row is referring to Senate district 8. So we can see that SD8 has an hPVI of D+6, that's because the way I've formatted the hPVI information a positive number means a Democratic lean and a negative number means a Republican lean. So a positive 6 means that SD8 is 6 points more Democratic than the State as a whole. I did it that way to make doing the math easier, not to imply that somehow a republican district is a negative thing. When you see a -10, it should be read as R+10.

This cell is also shaded slightly blue, for the hPVI information the cells are not solid blue or red, they are shaded depending on how the hPVI number relates to the others. So the cell representing the hPVI of SD8 is shaded slightly blue, because it's slightly more Democratic than average. You can see that the cell representing house district 8A is a deeper blue, this is because it has a higher hPVI and is more Democratic.

The column at the very end is the hPVI difference between the two house districts, how much of a partisan divide there is within the Senate district. SD8 has the largest divide of any Minnesota Senate district which is why it's solid green if the divide was smaller the cell would be less green and more white.

Here's another district in isolation:



So here we can see that all of the seats in district 56 are held by DFLers even though the hPVI of all the districts has a Republican tilt. And you can see in the last column that the two house districts have basically the same hPVI.

Here's another example:



Here you can see that SD57 and 57A are held by DFLers and 57B is held by a GOPer. SD57 has no partisan tilt, A is slightly Democratic and B is slightly Republican.

I hope that helps anyone who was confused.

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