15-SECOND TAKEAWAY
51 Democrats (+4) including 4 Leaners | 4 Tossups | 45 Republicans (-8) including 2 Leaners
50/51 Threshold is in the Leans D states: ME and IA
4 must-win states: AZ (Solid D), CO (Likely D), ME, NC (Lean D)
3 Breathing Room states: IA (Leans D), KS (Tossup), MT (Leans R)
Tossups are GA-regular, AK, SC, and KS.
Good News First
GA Jon Ossoff has been very close to Sen. Perdue for awhile, and in Aug. he split polls evenly, 1 Leans R, 1 Tossup and then 1 Leans D. It’s trending toward him, but Ossoff has a battle ahead. Anything you can do to help him might make the difference. Tossup
AK Dr. Al Gross is a rugged outdoorsman who worked his way through medical school as a commercial fisherman. He’s an Independent, but people expect him to caucus with the Democrats. Although he’s no liberal, a vote for Chuck Schumer is a vote for a Democratic majority. Hopefully he will be like another Angus King (I, Maine), rather than another Joe Manchin (D, West Va.). Tossup
NC The mainstream pollsters have been reporting good enough results for Cal Cunningham to put him at Likely D, bordering on Solid D. However East Carolina University has been producing its typical right-leaning polls, almost single-handedly keeping my tally at Leans D. I need to do an in-depth analysis on certain pollsters that are habitual outliers. Trafalgar is a definite plant for Trump and Spry Strategies is to a lesser extent. I'm not ready to ignore East Carolina just yet, though. Leans D
Now the Bad News
MT The only poll since July 31st shows Gov. Bullock has lost his lead and trails by 6 points, just inside 1.5 * MOE. We’ll hope for better polls, especially the one that counts. Leans R
MI Sen. Gary Peters is not a high-profile senator. He has been at Likely D or better most of the summer, but some weaker polls have dominated of late. Leans D
Background
To see recent polling developments in other Senate races, look at some of my other reports: 8/24, 8/8, 8/4, 7/31.
For those of you who haven’t followed my reports, here’s a brief explanation of how I categorize the state of each state race.
A word on my analysis methods…
I take all polls I can find from 270ToWin or 538 for the latest month polled, omitting any pollsters that have a noticeable bias (like Trafalgar, Spry, Gravis, or Rasmussen). To avoid a simple average without working a weighted average, I categorize each poll and then take the median of them to get a predominant category.
Stale states will stay in the same category until new polling comes in.
I categorize leads by this arbitrary set of rules:
My definition of a Tossup is a lead of +/- ½ margin of error (MOE). That means the leader has less than a 60% chance of truly leading. See Fig. 1 below.
I define Leaner as between ½ and 3/2 of the MOE, so the reported leader has between 59.9% and 77% chances of actually leading. See Figs. 1 & 2 below.
My Likely category is between 3/2 and 3 * MOE, so the leader has between 77% and 93% chance of being ahead.
My Safe category is only for leads at least thrice the MOE, so the leader has a greater than 93% chance of being ahead.
I am not doing any predicting, just blending any and all polls within the last month (or last month taken — if the last poll was in April and it’s now June, I’ll take the month of April) rated B/C or better by 538.
This is intended to give a snapshot of the horse race. Nothing more.
Figure 1. Lead = ½ the margin of error. Leader polls 48%, Trailer 46%, MOE 4%. Assume normal distribution and Trailer increases exactly match Leader decreases (undecided is constant). Probability of Leader really leading is the probability that his true percentage is 47 or higher (hence, the probability that the Trailer’s true chance is 47 or lower). From the graph, Prob = 59.87%
Figure 2. Lead = 1.5 x the margin of error. Leader polls 48%, Trailer polls 42%, MOE 4%. Assume normal distribution and Trailer increases exactly match Leader decreases (undecided is constant). Probability of Leader really leading is the probability that his true percentage is 45 or higher (hence, the probability that the Trailer’s true chance is 45 or lower). From the graph, Prob = 77.34%
Try out this and other scenarios at onlinestatbook.com/…
