Mark Blumenthal | October 26, 2006
Topics: 2006 , Slate Scorecard , The 2006 Race
After a long wait and a lot of hard work by the entire Pollster team, we are proud to unveil our new scorecard for races for the U.S. House of Representatives. We introduce the scorecard showing 219 seats in the Democratic column and 193 in the Republican column, with 23 seats showing neither candidate with a statistically meaningful lead. These numbers and how we got them deserve a bit more explanation, so here goes.
There are many different House scorecards available online that use a variety of different methods to try to estimate the outcome of control of the House. Some rely on subjective handicapping of individual races along with polling data, and some projective models use aggregate national data to forecast House seat counts. Our aim here is to simply summarize and aggregate the available District level survey data and let you reach your own conclusions.
Creating some sort of scorecard for the House is a lot more challenging than for races for the Senate and Governor because so few polls are available for House contests. As of today, we have collected public polls for 74 House seats, but that means that we have not been able to locate any public poll data for the remaining 361 contests (if you are aware of any public poll missing from our database, please do not hesitate to email us).
We like to average recent results here on Pollster, and House scorecard is no exception. On Senate and Governor scorecards (as well as the Election Scorecard we help produce for Slate) average the five most recent polls, and most of the closely watched Senate contests now have 5 or more new polls in the last 2 weeks. It is a very different story on the House side. Scroll through the House summary table and you will notice that roughly half of the districts three or fewer polls available for the entire campaign.
So we start by taking all of the available polling data and averaging across the most recent polls. We average the most recent polls available, but never more than the five. The "# in Avg" column in the summary table indicates the number of polls used to calculate the average.
To try to get an overall estimate of who leads in the race to control the House, we started by dividing the 435 seats into three categories.
- 85 seats considered competitive by the Cook Political Report as of October 20, 2006
- 184 non-competitive seats held by Democrats
- 166 non-competitive seats held by Republicans
For the purposes of the overall scoreboard, we have classified the non-competitive seats as "strong" Democrat or Republican based on the party of the incumbent. As of today, we have polls available for just seven of the non-competitive seats, and the results all show the incumbents with large leads. If we locate polling data indicating a real contest shaping up in any of the non-competitive districts, we will code it accordingly for the scoreboard.
We then focus more closely on the 85 competitive seats. Our classification system works the same as for our Senate and Governor scorecards. We rate races as "leaning" to a candidate if their lead is statistically meaningful (at least one standard error). If that lead is strongly significant (at least two standard errors), we rate the race as "strongly" Democrat or Republican.
For the U.S. House, we added a category named "no poll" for the competitive races for which we can find no available public polling data. Because most of these "no-poll" districts are among those considered only marginally competitive, we have classified them by the party of the incumbent member for purposes of the top-line scoreboard.
The color of the district labels on the map update automatically to reflect any changes in status. Dark blue and dark red represent races that we rate "strongly" Democratic or Republican respectively. Lighter shades indicate a lean status. States colored yellow are those we classify as "tossups"- races in which neither candidate shows a significant lead over the last five polls. No-poll competitive races are grey.
We are still at work preparing charts for all of the 74 House races. For now, links on the map or in the summary table will take you to a table in the page below with individual poll data and links to source pages.
Finally, note that you can sort the summary table by any of its data, by clicking on the column heading of the category of interest.
I'll have more posts in the next day or so explaining, as best I can, some of the limitations of this data and what it all means. Stay tuned.