RCP Averages by Bifurcated Results (What's Going On Here?)

[UncleNoel]

RCP Averages by Bifurcated Results (What’s Going On Here?)

I took the most recent four polls for two very different sets of results from RCP (adding in David Binder Research poll). The criteria for separating the two groups was simple those that had double digit leads for Biden and those that did not. The two sets are starkly different. Can anyone tell me what factors go into having two sets of totally different results? UPDATED with latest HarrisX

I.Biden with double digit leads

HarrisX (9/29-Oct 2) Biden 32% Warren 22% Sanders 14%
Politico/Morning Consult (9/23-9/29) Biden 32, Warren 21, Sanders 19
Harvard/Harris (9/22-9/24) Biden 28, Warren 17, Sanders 16
David Binder Research (9/19-9/22) Biden 34, Warren 17, Sanders 15
Averages: Biden 31.5, Warren 19.25, Sanders 16 (Biden +12)

II.Biden slipping, Warren surging

Economist/YouGov (9/28-10/1) Biden 22, Warren 28, Sanders 7
Monmouth (9/23-9/29) Biden 25, Warren 28, Sanders 15
Emerson (9/21-9/23) Biden 25, Warren 23, Sanders 22
Quinnipiac (9/19-9/23) Biden 25 Warren 27, Sanders 16
Averages: Biden 24.25, Warren 26.5, Sanders 15 (Warren +2)

What factor or factors go into this bifurcated polling?

[aikoaiko]

1. Opinions are in flux, but appear to be moving in a direction

[Demsrule86]

5. wishful thinking polls. Biden is ahead and will be the nominee and the next president.

[aikoaiko]

7. A little wish, but a lot of data showing warren is catching up the Biden in a hurry.

https://photos.google.com/album/AF1QipMIXb8lpPzdBfpuo7338Hw_pX2tD1Djf9zGOYRu/photo/AF1QipNmraGfWq-mlgzka2npBjwpftggKmrMU04eUPjj

[Demsrule86]

12. I don't see it...the polls that show her ahead are mostly those internet types or with tiny

number of people surveyed...Biden is still ahead...which is why we here about momentum...media rooting for Warren.

[GeorgeGist]

10. I doubt Biden's 30% will be enough to offset Warren + Sanders

[BlueMississippi]

2. I think the sample weights are different.

Group I is probably heavy with Southern and Midwestern voters and Group II is probably heavy with Northeastern and Pacific state voters.

[UncleNoel]

3. Sounds likely

Wish I had the time to research each of them to see the sample areas, etc.

[dlk]

4. With polls, it's always important to consider the statistical significance of the sample

Who gets polled greatly impacts the results.

[ritapria]

6. This is crazy

Economist/YouGuv has Bernie at 14%, not 7% ….. I am confounded... Are these pollsters polling the same nation ? FWIW , a new Public Policy Institute Poll has CA at Warren 23% Biden 22% Bernie 21% Harris 8% It would helpful for Nate Silver to weigh in on this polling bifurcation issue ……. Change Research has just published a poll for AZ : Warren 35% Bernie 18% Biden 15% Buttigieg 13% Yang 8% Harris 4% …….Change Research always produces results very favorable to Warren and very unfavorable to Biden …….I am sure Joe is doing better in AZ than their polling indicates …..I try to remain objective on my analysis even though I am for Bernie …..

[peggysue2]

13. LOL!!

Think you hit it on the head here:

Are these pollsters polling the same nation?

The polls really are all over the place. So . . . you're not the only one confounded.

[honest.abe]

8. National polling for a Presidential primary is somewhat meaningless anyway.

What always happens is the winners of the early primaries get a huge boost to the next primaries making any past polling irrelevant.

I wish the pollsters would do more early state polling (the "big" first 4) and the Super Tues states. That would be more telling.

[Funtatlaguy]

9. I don't think RCP uses all polls in its averaging.

[Skya Rhen]

11. Group I uses large sample sizes and Group II uses small sample sizes.