The 2022 midterm elections are upon us. Usually the party that is out of power gains seats but this year may be different. Above is the list of recent generic congressional polls published by Real Clear Politics (RCP). The question in these polls generally take the form, “In general, for whom do you plan to vote in the upcoming 2022 congressional election? Democrat, Republican or undecided?” The RCP average of these polls says that Democrats are 0.4% ahead. How does poll sample selection method influence their results?
The above graphic also gives sample size with the letters RV or LV next to them. RV means registered voters in the sample and LV means likely voters. A positive mean means that Democrats have the advantage while a negative mean means that Republicans have the advantage.
| t-Test: Two-Sample Assuming Equal Variances | ||
| Registered Voter | Likely Voters | |
| Mean | 2 | -3 |
| Variance | 12 | 10 |
| Observations | 8 | 4 |
| Pooled Variance | 11.4 | |
| Hypothesized Mean Difference | 0 | |
| df | 10 | |
| t Stat | 2.42 | |
| P(T<=t) two-tail | 0.04 |
The above table shows the difference between the mean differences across 4 likely voter surveys and 8 registered voter surveys. For the likely voter surveys, Republicans have a 3% advantage. For the registered voter surveys, Democrats have a 2% advantage. This difference is statistically significant with a two tailed p value less than 0.05.
Pennsylvania Senate Race
Above are the RCP published polls in the PA Senate race between Lt. Gov. John Fetterman and Dr. Mehmet Oz. Eyeballing the samples used in these polls, the two registered voter polls give Fetterman an average 12% advantage while the 5 likely voter samples give him an average 5.6% advantage over Oz. This difference in survey sample size types is also statistically significant.
Five Thirty Eight currently projects that there is a 70% probability of the Democrats holding on to the Senate and a 74% probability of the Republicans retaking the House or Representatives. For the House, the GOP’s forecasted advantage is at least partly due to gerrymandering and many representatives running unopposed. Getting more “unlikely” voters to the polls this November will help the Democrats in congressional and state legislature races throughout the U.S.
On an unrelated subject, I will be at the Cambria County Arts and Heritage Festival at Duman’s Lake Park this weekend to sell my book and cover the festival. You’re all welcome.