The Media and 270ToWin seem to be sticking to their expectations of a near 50-50 Senate over the polls, which predict something in the neighborhood of 53-47 +/- 3.
Perhaps they want to build the story of a surprise to bump Nov 8 ratings. Perhaps they are wary from 2016 and 2020 Senate and particularly House results coming out skewed to the right of polls.
Method
This is my quick method of poll analysis. Not doing rigorous statistics to combine polls. Typically, polls have a 95% confidence margin of error in the 3 to 5 percentage point range. I find the average of poll margins and compare it against fixed thresholds based on 4%:
- < 2 percentage pt. margin = Tossup (much less than 95% confident either candidate is leading)
- 2 to 4-point margin is a Lean (270’s gray-blue or gray-pink)
- 4 pt. < margin <= 8 pt. is a Mild Lead (baby blue or pink) (more than 95% confident)
- 8 pt < margin <= 12 pt. is a Solid Lead (blue or red)
- Margin > 12 points is a Prohibitive Lead (dark blue or dark red)
I review the polls reported on 538, as they tend to be a superset of those on 270ToWin. For each race, I look back 1 to 2 months. Right now, I am collecting August and early September polls. If I have fewer than 3 unbiased polls from that time range, I go back to July. I do an average of unbiased polls, then I do a second set including biased polls that were taken during the same time frame. See discussion of biased polls below. I compare the averages to the thresholds above to find a category(ies). If the unbiased and combined polls differ in category, then I take the one that is less certain (closer to gray). However, if all the biased polls are from only one side, then I go back up to 2 months in time to get the other side, or I rate that average one category less favorable to the side of the bias.
Biased polls include those marked by 538 as funded by a party or candidate. I particularly find that Trafalgar Group, Rasmussen (haven’t seen any this year, I think they changed their name in 2020) and John Bolton Super Pack are actually quite biased in favor of Republicans. Usually the Democratic polls are neutral or even slightly pessimistic to Democrats. Emerson College polls are not marked as biased, but they often show 5 or 6 points bias in favor of Republicans. I am counting them as unbiased. Interestingly, Fox Lies polls are pretty unbiased, and they are counted as such.
When a pollster does multiple polls at once with different criteria (LV, RV, A, or with and without 3rd-party candidates), I throw out any All Adults polls, average the rest and count it as 1 poll. I prefer post-primary polls when there is a question about how many polls to consider.
Changes
Changes since my last analysis, which was less exact in process and which used 1.5, 4, 9, and 14 pt thresholds.
The Democratic Senate caucus slips from 54 counting leaners to 53. Republicans hold at 46.
Georgia slips from leaning D to Tossup, on strength of biased polls from Trafalgar and Emerson College showing Heismann Trophy winner Walker with 1 or 2 point leads. It’s been two months since a poll has shown Sen. Warnock with a double-digit lead. 538 still shows a 1.7 pt lead for Warnock.
Tim Ryan pulls Ohio into Mild D category on the basis of Center Street polls over Trafalgar and Emerson College polls.
Indiana is finally polled (by Democrat McDermott) and shows him trailing by just 3 points! Presumptive dark red is replaced by pink (Mild R). (Would be Lean R, but poll is presumed biased.)
Missouri moves to Solid R as post-primary polls show Trudy Busch Valentine trailing by double digits.
New Hampshire shows just a Lean D with my more exacting method, ahead of primaries.
An Illinois Senate poll puts Sen. Tammy Duckworth up by 23, not 9 like a July poll. Prohibitive D
Just the Polls, Maam
Despite continued “expert consensus” to the contrary, polls continue to show:
- FL just leans R for Sen. Rubio, not even a Mild Lead over Rep. Val Demings.
- NC leans D for Chief Justice Cheri Beasley.
- WI Lt. Gov. Mandela Barnes has a Mild lead over Sen. Johnson.
- AZ Sen. Mark Kelly has a Solid lead.
- PA Lt. Gov. John Fetterman has a Solid lead over Dr. Mehmet Oz of NJ.