I saw a headline today saying that Republicans had made some gains in the Senate contest. So I decided to update the polls and see what tale they had to tell.
The previous analysis from 12 days ago gave the Democrats a 98.1% probability of taking the Senate with a mean of 51 seats.
With today’s polls, after 100000 simulated elections, Democrats have a Senate majority 74100 times, there were 23093 ties), and Republicans control the Senate 2807 times. Democrats have a 97.2% probability of controlling the Senate and Republicans have a 2.8% probability of controlling the Senate. So, I guess there was a tiny movement toward Republican control.
Some states, like Colorado, Illinois, and New Hampshire, have moved a bit more into the Democrat column. But Ohio, Pennsylvania and Wisconsin have gone the other way. It is almost a wash.
Here is the distribution of Senate seats from the simulations:*
This graphs shows the probability of at least each number of seats controlled by the Democrats:*
- 100000 simulations: Democrats control the Senate 97.2%, Republicans control the Senate 2.8%.
- Average ( SE) seats for Democrats: 51.2 ( 1.1)
- Average (SE) seats for Republicans: 48.8 ( 1.1)
- Median (95% CI) seats for Democrats: 51 (49, 53)
- Median (95% CI) seats for Republicans: 49 (47, 51)
Expected outcomes from the simulations:
- Democratic seats w/no election: 34
- Independent seats w/no election: two
- Republican seats w/no election: 29
- Contested Democratic seats likely to remain Democratic: 13
- Contested Republican seats likely to remain Republican: 20
- Contested Democratic seats likely to switch: one
- Contested Republican seats likely to switch: one
This table shows the number of Senate seats controlled for different criteria for the probability of winning a state:* Safe>0.9999, Strong>90%, Leans>60%, Weak>50%
|Threshold||Safe||+ Strong||+ Leans||+ Weak|
This table summarizes the results by state. Click on the poll number to see the individual polls included for a state.
|State||@||polls||size||Democrat||Republican||% wins||% wins|
@ Current party in office
& An older poll was used (i.e. no recent polls exist).
*Analysis assume that independent candidates will caucus with the Democrats.
Details of the methods are given in the FAQ.