Are federal elections in the US inherently likelier to be Republican than Democratic victories?

[Vosem]

epistemic status: 70% serious, 30% kidding, but the data does add up

America has two kinds of elections that the entire country participates in simultaneously: presidential elections and House elections. People tend to vote similarly in both kinds of races and only rarely split their ballots for exceptional candidates (even if they support a different party at the state level). Since 2000*, Republicans have won these elections more often than Democrats:

Republican victories (11): 2000-House, 2000-POTUS, 2002-House, 2004-House, 2004-POTUS, 2010-House, 2012-House, 2014-House, 2016-House, 2016-POTUS, 2022-House
Democratic victories (7): 2006-House, 2008-House, 2008-POTUS, 2012-POTUS, 2018-House, 2020-House, 2020-POTUS

11 to 7 is a pretty decent advantage. If you shift these results to popular vote, though, something different emerges:

Republican victories (8 ): 2000-House, 2002-House, 2004-House, 2004-POTUS, 2010-House, 2014-House, 2016-House, 2022-House
Democratic victories (10): 2000-POTUS, 2006-House, 2008-House, 2008-POTUS, 2012-House, 2012-POTUS, 2018-House, 2020-House, 2020-POTUS

Democrats now win, but it's 10-8 -- a slightly smaller advantage. (If you literally average all these elections out, then you get an average result of ~D+1).

My question is -- are Republicans just inherently more likely to win national elections in the US? If we are forecasting a national election, should we say that there is roughly a ~60% chance that it will be a Republican victory before any campaigning happens? (And a similar roughly ~60% chance that it will be a Democratic popular vote victory, perhaps?)

(There is a distinction here between presidential races and House races, but it mostly shows up in the popular vote, where presidential races are 4-1 D while House races are still 7-5 R. Using actual winning, you have a 3-3 tie presidentially while House races are 8-4 R. Is there a reason Republicans should do better in House races and Democrats in presidential races? When we hold elections concurrently, the pattern is a little weak -- House Republicans did better than their presidential candidate in 2000/2012/2016/2020, but worse in 2004/2008.)

^{*This is an arbitrary cut-off, but it doesn't really matter where you put it; if you go backwards, you hit a tie in 1978 and a Democratic advantage in 1976. If you move forward, you get Democratic advantages in 2006/2018/2020, and ties in 2008/2016; for most starting years the result is roughly the same.}

[OSR stands with Israel]

I would not include 2000-2004 here cause things clearly did change from 2006 onwards. I would say things go like this


1932-1968: Democratic Dominance
1968-1980: Mixed(1968-1974 was a slight Republican advantage while 1974-1980 was Democratic Dominance)
1980-2006: Republican Advantage
2006-2020: Democratic Advantage


So including 2000, 2002, 2004 wins here cause they were clearly held at a time when there was a Republican Advantage and 1994-2006 is arguably the best period for conservatives electorally in modern US history.

[Torie]

The margins are narrow enough, and the sample small enough, and each election cycle dissimilar enough, that I don't think there is much statistical significance to be had out there.

That said, rate candidate quality for each POTUS nominee, and where one party has an edge over the other, assign a headwind or tailwind to that, and maybe aside from the small sample size, that might bring some order to the randomness. It was probably pretty even in 2000 and 2004, with the candidates being mediocre (Dubya, Gore and Kerry), then Obama had a fairly sizable edge over the gunslinger impulsive McCain and the then Ken Doll like patrician Mittens, and then there were two about equally bad candidates in 2016, and in 2020 also two subpar candidates, but by this point, Trump had moved on to near horrifically bad, while Biden was more of just the benign null set.

I yearn for the good old days of GHWB and Bill Clinton. Where have all the flowers gone?

[politicallefty]

It is a rather arbitrary cutoff (and certainly too small of a data set to make serious claims). I think a better start would've been 1992. It lines up well with the end of the 40-year Democratic House Majority and the beginning of a new political paradigm. It would've added three wins to each in terms of actual wins, but a 4D-2R advantage in the popular vote.

You can't look at the House without considering gerrymandering and Republicans have had the advantage for decades now (the Republican gerrymanders after the 2010 Census being the most extreme). There's a very strong case to be made that gerrymandering cost Democrats the House this year. I think you can also make the case that that is also so for 2012 as well, though it would've been close either way. Clinton's win in 1996 is also more disappointing when you consider his failure to win back the House (and Democrats were not in a deep hole after 1994).

If you look at the popular vote of the 16 House elections over that timespan, you have half that are close (no more than 3.1%). Of the remaining half, two are more moderate wins, one for each party. When you get to the big wins, the split is 3-3, with the Democratic wins being significantly larger. (I think 2014 is debatable in that category in terms of the popular vote and it probably could be dropped down into the "moderate" category.)

Waves:
1994: R+6.8%
2006: D+8.0%
2008: D+10.6%
2010: R+6.8%
2014: R+5.7%
2018: D+8.6%

Moderate:
1992: D+5.0%
2002: R+4.8%

Closest:

1996: D+0.07%
1998: R+1.1%
2000: R+0.5%
2004: R+2.6%
2012: D+1.2%
2016: R+1.1%
2020: D+3.1%
2022: R+2.8%

Overall, in terms of the House, I think it's a wash. While Republicans did have success in holding their majority in three successively close elections after 1994, I definitely think gerrymandering is overstating Republican strength over the past decade. It would be interesting if the House really starts lining up with the presidential winner.

[Arizona Iced Tea]

Ceteris paribus, assume the most generic R and the most generic D running for President in an open race. No scandals, and neither candidate is weak nor strong. Who do you think wins?

[Alben Barkley]

The margins are narrow enough, and the sample small enough, and each election cycle dissimilar enough, that I don't think there is much statistical significance to be had out there.

That said, rate candidate quality for each POTUS nominee, and where one party has an edge over the other, assign a headwind or tailwind to that, and maybe aside from the small sample size, that might bring some order to the randomness. It was probably pretty even in 2000 and 2004, with the candidates being mediocre (Dubya, Gore and Kerry), then Obama had a fairly sizable edge over the gunslinger impulsive McCain and the then Ken Doll like patrician Mittens, and then there were two about equally bad candidates in 2016, and in 2020 also two subpar candidates, but by this point, Trump had moved on to near horrifically bad, while Biden was more of just the benign null set.

I yearn for the good old days of GHWB and Bill Clinton. Where have all the flowers gone?

Agreed with the last part at least. But Hillary was not "equally bad" as Trump, not even as just a candidate. Comey killed her and the electorate failed her. There was no universe in which she should have lost that election, she was the most qualified candidate in history.

[OSR stands with Israel]

The margins are narrow enough, and the sample small enough, and each election cycle dissimilar enough, that I don't think there is much statistical significance to be had out there.

That said, rate candidate quality for each POTUS nominee, and where one party has an edge over the other, assign a headwind or tailwind to that, and maybe aside from the small sample size, that might bring some order to the randomness. It was probably pretty even in 2000 and 2004, with the candidates being mediocre (Dubya, Gore and Kerry), then Obama had a fairly sizable edge over the gunslinger impulsive McCain and the then Ken Doll like patrician Mittens, and then there were two about equally bad candidates in 2016, and in 2020 also two subpar candidates, but by this point, Trump had moved on to near horrifically bad, while Biden was more of just the benign null set.

I yearn for the good old days of GHWB and Bill Clinton. Where have all the flowers gone?

Agreed with the last part at least. But Hillary was not "equally bad" as Trump, not even as just a candidate. Comey killed her and the electorate failed her. There was no universe in which she should have lost that election, she was the most qualified candidate in history.

There is no way she was more qualified than LBJ or Nixon and frankly Reagan’s resume was more impressive for president given being Governor of a large state that was Lean R at most for 8 years is more directly related to the job of president than senator or even sec of state.


Calling her the most qualified candidate in history is lol worthy and an example of liberal media bias

[Orser67]

I think the difference in this particular time period primarily comes down to the unusually strong 2002 Republican midterm election, which itself was primarily the result of a black swan event that has little to do with the inherent strength of either party. I think there's a pretty good chance that a normal midterm sees Democrats win the House in 2002 and keep it in 2004, despite Bush's re-election (much like 1996 and 2012). Flip those two elections, and the "score" is 9-9.

Republicans also had some luck with a well-timed wave election in 2010, which may have helped them keep the House in 2012 and 2016.

[Schiff for Senate]

For House races, did you account for uncontested races? Like House races where the GOP candidate didn't face a Democratic opponent (in 2022, that would include, among many others, two House seats in Southwestern PA, another in the Jacksonville area, and another in WI08), or races where the Democratic candidate didn't face a GOP opponent (which would include, among many other races, AL07 in 2014, 2016, 2018, and 2020, and Alma Adams' district in 2020).