Get more FiveThirtyEight
- Terms of Use
- Privacy Policy
- Your California Privacy Rights
- Children's Online Privacy Policy
- Interest-Based Ads
© 2018 ABC News Internet Ventures. All rights reserved.
Chance the Democrat wins (>99.9%)
Chance the Republican wins (<0.1%)
The Classic version of our model projects a race’s outcome by taking a weighted average of polls of the race (if available), polls of similar races (CANTOR) and non-polling factors (fundamentals). It is then reverted toward a mean based on long-term trends in midterms and presidential approval ratings.
D+33.6
Adjusted polls
D+24.3
CANTOR
D+39.3
Fundamentals
D+36.0
Experts
D+31.9
Lite
D+35.5
Classic
D+35.7
Deluxe
<0.1
<0.1
Historical adjustment
Key
More weight
Less
We've collected two polls for the Maryland Senate election. We’re adjusting poll results in three ways: Polls of registered voters or all adults are adjusted to a likely-voter basis; older polls are adjusted based on shifts in the generic congressional ballot since the poll was conducted; and polls are adjusted for house effects (the tendency for a firm’s polls to lean toward Democrats or Republicans). Polls with larger sample sizes and those conducted by higher-quality polling agencies are given more weight, as are more recent polls.
Adjustments | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
dates | pollster | sample | weight | Cardin | Campbell | margin | likely voter | Time-line | House effects | Adjusted margin | |
Oct 1-6 10/1-6 | Gonzales Research & Marketing Strategies Inc. I | 806 | LV | 0.99 | 49% | 22% | D+27.9 | — | <0.1 | 3.5 | D+31.4 |
Sep 11-16 9/11-16 | Goucher College | 472 | LV | 0.63 | 56% | 17% | D+39.0 | — | 0.1 | 2.2 | D+36.7 |
Our state similarity scores are based on demographic, geographic and political characteristics; if two states have a score of 100, it means they are perfectly identical. These scores inform a system we use — CANTOR, or Congressional Algorithm using Neighboring Typologies to Optimize Regression — to infer what polling would say in unpolled or lightly polled states, given what it says in similar states.
Sim. score | Polling avg. | ||
---|---|---|---|
Delaware | 64 | D+20.8 | |
New York | 61 | D+24.7 | |
New Jersey | 58 | D+10.1 | |
Connecticut | 55 | D+18.8 | |
Virginia | 52 | D+14.1 | |
Illinois | 50 | — | |
Massachusetts | 50 | D+23.2 | |
Pennsylvania | 36 | D+11.7 | |
Rhode Island | 31 | D+22.2 | |
California | 28 | — | |
Minnesota (special) | 26 | D+8.5 |
The Deluxe version of our model calculates an implied margin for each race based on expert race ratings from The Cook Political Report, Inside Elections and Sabato's Crystal Ball; it then adjusts that margin toward its estimate of the national political environment.
Equivalent Margin | |||
---|---|---|---|
Expert | rating Rating | Raw | Adjusted |
Cook Political Report | D+35.6 | D+36.2 | |
Inside Elections | D+35.6 | D+36.5 | |
Sabato's Crystal Ball | D+35.6 | D+35.2 | |
Average | D+35.6 | D+36.0 |
Nate Silver explains the methodology behind our 2018 midterm forecasts. Read more …
Comments