Sunday, November 09, 2008

House Forecast Review

WE'VE MOVED! Democratic Convention Watch is now at

We've been tracking various House forecasts all year long, and now it's time to grade each of the forecasts, as well as how DCW's overall forecast did. (Although we didn't track Open Left during the year, we'll grade their final forecast also).

Our overall forecast was for a gain of 21.2 seats. Currently, Dems have picked up 20 seats, and will likely gain 1-2 more. If that happens, then the overall forecast could have been any more accurate!

We also graded each individual forecast. We gave each forecast a value of 0-1 points for every seat it predicted. (See formula at bottom). We looked at 81 seats that at least one forecast rated Lean or Tossup.

Rothenberg: Grade: A. Score 68.4 (out of 81)

Best Predictions:
AZ-3: Rep-Strong (everyone else had it as Rep-Lean). There was a lot of chatter that John Shadegg's seat might be in jeopardy. Shadegg won by 12 points, 54-42.

IN-3: Another seat at Rep-Strong that others had Rep-Lean or Tossup. Souder won 55-40.

NV-2: Again alone at Rep-Strong. Heller won by over 10 points

Worst predictions:
AK-AL: Even if Berkowitz pulls it out, a Dem-Strong rating is still wrong.
GA-8: Called it a Tossup. Marshall won by 14.

Open Left (60.9), Swing State Project (60.6), Cook (60.2): Grade: B.

Best Predictions:
Cook: AK-AL. Only one to have it as a Tossup.
Open Left: IL-11. Only one at Dem-Strong. Halvorson won by 24.

Worst Predictions:
Cook: CO-4. Only one to have it as a Tossup. Markey won by 11.
Open Left: LA-6. Had it at Dem-Strong. Cazayoux lost by 8.
SSP: IN-3. Had it as a Tossup. Souder won 55-40.

CQ (54.3), Crystal Ball (53.9): Grade: C.

Worst Predictions:
Crystal Ball: IL-10. Had it at Dem-Lean. Kirk won by 9 points.
CQ: NM-2. Had it at Rep-Lean. Teague won by almost 10 points.

We hope you found the House Forecast useful. We'll be starting the 2010 House Forecast in the near future.

We gave a value for each forecast's prediction of each seat, as follows:
If a seat was rated a tossup, we gave a 1.0 points if the race ended up under 5%, 0.5 points if the race was between 5% and 10%, and 0.1 point if the race ended between 10% and a 15% lead.

If a seat was rated as Lean, we gave 1.0 points, if the party rated lean won with a 0-10% lead, 0.5 points if the party won with a lead between 10 and 15% or lost by 0-5%, 0.25 points if the party won with a lead 15% or greater, and 0.1 if the party lost with a lead between 5 and 10%.

If a seat was rated safe or strong, we gave 1.0 points if the party won with a 5% or greater lead, 0.5 points if the party won with a lead of 0-5%, and 0.1 points if the party lost with less than 5%.