Senate outlook: 45-50 Democratic / Independence seats (average = 47)
November 2, 2018, 10:47 am by Sam Wang
If the error of systematic voting is not greater the last midterm election (3 percentage points average, 5 points maximum), control of the Senate seems like a difficult step for Democrats. Voting error would have to be 5.0 points or more (that’s how the Meta-Margin is determined).
Since Meta-Margin has been stable for about two weeks, I have created a table displaying the polls with an end date of October 19 or later. The means of probing are given with the standard error of the mean (SEM).
The lead is then converted to sigma units by combining the SEM and the mean historical error (3 points) into a single quantity, the sigma. Therefore, Sigma not only includes sampling error but also systematic error, i.e. who polls on who ended the voting. Conceptually, the lead is 2.0 sigma which corresponds to the margin of error in a poll.
|State||Leader||Median +/- SEM (n)||# sigma lead|
|MT||Tested||D + 8.0 ± 2.1% (3)||2.2 sigma|
|NJ||Menendez||D + 5.0 ± 1.0% (3)||1.6 sigma|
|FL||Nelson||D + 2.0 ± 0.7% (17)||0.6 sigma|
|NV||Rosen||D + 2.0 ± 3.1% (8)||0.5 sigma|
|THE||McSally||R + 1.0 ± 1.3 (9)||0.3 sigma|
|MO||Hawley||R + 1.5 ± 1.2 (4)||0.5 sigma|
|IN||Braun||R + 2.0 ± 1.7 (6)||0.6 sigma|
|TX||Cruz||R + 4.5 ± 1.0 (6)||1.4 sigma|
|TN||Blackburn||R + 6.0 ± 0.9 (6)||1.9 sigma|
|ND||Cramer||R + 9.0 ± 2.3 (3)||2.4 sigma|
Within the 2 sigma range are eight giant races. The range covers everything from losing Menendez in New Jersey to victories in Texas and Tennessee for O’Rourke and Bredesen. However, these extreme possibilities seem unrealistic. Voter turnout should be high, making it a little easier for polls to judge qualified voters.
It seems to me that a series of more realistic uncertain races add or subtract 3 percentage points: Florida, Nevada, Arizona, Missouri and Indiana. In that case, the result range is 45 to 50 Democratic / Independent seats. The average result is 47 seats D / I, a real change of two seats. It’s good for the Republicans they’re running for in such red states this year.
There could be a 50-50 odds of gaining control of the Senate if the Democrats win all of these close races. It’s not crazy at all because the races are close tend to break the same way – usually in the direction of the winner. If that outside possibility happens, I wonder if there will be a share of power in the Senate, as there was in 2001, or if the Republican caucus would use Vice President Pence as a human. decide to maintain control.
For Democrats, the ActBlue link on the left has been updated to reflect these close races. For Republicans, the NRSC page is still a good place to give.