Cook Releases 2008 PVIs, With a Change SSPers Will Like

Our friends at the Cook Political Report have released an updated Partisan Voting Index that now includes the results of the 2008 presidential election. They’ve also made a small change in the formula used to calculate PVIs, and I think it’ll be instantly recognizable to SSPers:

To determine the national average for these latest ratings, we have taken the average Democratic share of the two-party presidential vote for 2004 and 2008, which is roughly 51.3 percent, and that of Republicans, which is roughly 48.7 percent. So, if John Kerry captured 55 percent of the vote in a district and Barack Obama carried 57 percent in the district four years later, the district would have a PVI score of roughly D+5. (Emphasis added.)

As we discussed at length, the old PVI formula compared district-level results for the past two presidential elections to nationwide results for only the most recent election. This choice sparked plenty of debate, and some folks even suggested we use our own “SVI” that would compare 2004 to 2004 and 2008 to 2008.

Fortunately, the debate has been resolved. As you can discern from the description above (the key part is in bold), Cook has decided to revise its methodology along the lines proposed by people here. Charlie Cook (an SSP reader, as is House editor David Wasserman) told me he wanted something that was “totally apples and apples,” and I agree with the choice. Ultimately, this means that the new PVIs will be about two points bluer than under the old system – e.g., a district that would have been R+10 will now come in at R+8.

You can find the new PVIs by partisan rank in this PDF, as well as by member name and by state/district. There’s also a giant-size map and a cool chart showing trends in the PVI over the last decade. (As you’d expect, the number of “competitive” districts, at least on the presidential level, has been shrinking.) Have fun!

30 thoughts on “Cook Releases 2008 PVIs, With a Change SSPers Will Like”

  1. two-cycle meaning that we use numbers from the two most recent presidential elections.

  2. in order from most Democratic to most Republican.

    Obama-Republican districts are bolded.

    CA-09 (Lee-D): D+37

    CA-08 (Pelosi-D): D+35

    CA-33 (Watson-D): D+35

    CA-35 (Waters-D): D+31

    CA-31 (Becerra-D): D+29

    CA-37 (Richardson-D): D+27

    CA-28 (Berman-D): D+23

    CA-06 (Woolsey-D): D+23

    CA-12 (Speier-D): D+23

    CA-13 (Stark-D): D+22

    CA-34 (Roybal-Allard-D): D+22

    CA-14 (Eshoo-D): D+21

    CA-07 (George Miller-D): D+19

    CA-17 (Farr-D): D+19

    CA-38 (Napolitano-D): D+18

    CA-30 (Waxman-D): D+18

    CA-16 (Lofgren-D): D+16

    CA-15 (Honda-D): D+15

    CA-05 (Matsui-D): D+15

    CA-32 (Open [Solis] -D): D+15

    CA-53 (Davis-D): D+14

    CA-29 (Schiff-D): D+14

    CA-01 (Thompson-D): D+13

    CA-43 (Baca-D): D+13

    CA-27 (Sherman-D): D+13

    CA-39 (Linda Sanchez-D): D+12

    CA-23 (Capps-D): D+12

    CA-36 (Harman-D): D+12

    CA-10 (Tauscher-D): D+11

    CA-51 (Filner-D): D+8

    CA-20 (Costa-D): D+5

    CA-47 (Loretta Sanchez-D): D+4

    CA-18 (Cardoza-D): D+4

    CA-11 (McNerney-D): R+1

    CA-50 (Bilbray-R): R+3

    CA-26 (Dreier-R): R+3

    CA-45 (Bono Mack-R): R+3

    CA-24 (Gallegly-R): R+4

    CA-03 (Lungren-R): R+6

    CA-46 (Rohrabacher-R): R+6

    CA-48 (Campbell-R): R+6

    CA-25 (McKeon-R): R+6

    CA-44 (Calvert-R): R+6

    CA-40 (Royce-R): R+8

    CA-19 (Radanovich-R): R+9

    CA-52 (Hunter Jr.-R): R+9

    CA-42 (Gary Miller-R): R+10

    CA-49 (Issa-R): R+10

    CA-04 (McClintock-R): R+10

    CA-41 (Lewis-R): R+10

    CA-02 (Herger-R): R+11

    CA-21 (Nunes-R): R+14

    CA-22 (McCarthy-R): R+16

  3. tells you what you need to know about how this map tilts. Democrats have some work to draw in a couple of years.  

  4. Both the 2004 and 2008 elections results are the factors to the PVI results, do you think that the race issue during the 2008 presidential race threw off the numbers? Oklahoma, Tennesee, Arkansas and a couple other states actually took a significant turn to the right during the 2008 cycle despite the rest of the country going in the other direction, (presumably due to President Obama’s race), are those PVI’s accurate or should we be more skeptical?

  5. Cook’s cool chart showing the breakdown of districts by PVI really shows how Democrats got screwed in the 2000 redistricting.  In 2000, there were 142 heavily Republican leaning districts (PVI >5) and 134 heavily Democratic leaning districts, only 8 more R than D safe districts.  In 2010, there are 182 heavily Republican leaning districts compared to 149 Democratic ones; 33 more R than D safe districts.  That is a direct result of us losing the 2000 (and post-2000 in the case of TX) redistricting wars.  We can and must do better in 2010!

  6. I’m surprised to read that the methodological change would tend to produce PVIs that are about 2 points bluer.

    The new PVIs for Iowa are:

    IA-01 D+5 (was D+4)

    IA-02 D+7 unchanged

    IA-03 D+1 unchanged

    IA-04 Even (was D+0)

    IA-05 R+9 (was R+8)

    Iowa’s presidential results have been pretty close to the national presidential results in 2000, 2004 and 2008.

    I wonder why the Iowa PVIs mostly did not get bluer. Does anyone on this board have a hypothesis for me?

  7. For the record, DavidNYC should get the credit for our decision to change the formula for calculating the Partisan Voting Index.  

    We started the PVI 12 years ago and frankly, when DavidNYC emailed me asking why we compared the two previous elections nationally with just the most recent presidential result in each CD, I could not remember why we decided to do it that way to begin with.  

    Our House Editor, David Wasserman and I discussed it with Clark Benson from Polidata, the firm that compiles and computes the presidential vote data for us and together decided to make the switch.  As DavidNYC points out, it changes few districts, but is a better way to do it.

    Though the Cook Political Report has been around for 25 years (as of last month), we still try to view things through fresh eyes each election cycle and welcome constructive suggestions.

    Charlie Cook

    1. CA-46’s swing from Bush 2004 to Obama was a little less than the Obama-Republican districts had, as well as McNerney’s since his district is somewhat similar to the O-R districts partisanship-wise, and the swing was not enough to make it another O-R district.

      CA-44 swung from Bush by 19 to Obama by 1, a swing of 20 points to Obama.

      CA-25 also swung from Bush by 19 to Obama by 1, a swing of 20 points.

      CA-48 swung from Bush by 18 to Obama by 1, a swing of 19 points.

      CA-03 swung from Bush by 19 to Obama by 1, a swing of 20 points.

      CA-24 swung from Bush by 13 to Obama by 3, a swing of 16 points.

      CA-45 swung from Bush by 13 to Obama by 5, a swing of 18 points.

      CA-26 swung from Bush by 12 to Obama by 4, a swing of 16 points.

      CA-50 swung from Bush by 11 to Obama by 4, a swing of 15 points.

      CA-11 swung from Bush by 9 to Obama by 9, a swing of 18 points.

      CA-46 swing from Bush by 15 to McCain by 2, a shift of 13 points.

  8. Sure there are plenty of ways to compute some kind of partisan index for CD’s using other races, but they would only be useful for intra-state comparison.  Using different races in different states would not be comparable across state lines, which is what we wanted to do.

    Actually senatorial and gubernatorial races are often not the best races to use to compute partisan voting behavior, as they are affected by the personalities of the candidates and the campaigns.  Better are low visibility, down-ballot statewide races where no one really knows who most of the candidates are, they are just voting on party.  

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