Monthly Archives: July 2019

THE GENERIC BALLOT: SEAT ALLOCATION VS THE POPULAR VOTE (PART 2)

The 2020 elections are still 16 months away and yet pollsters are out in force, giving us just enough information to break out our crystal balls and make wildly irresponsible predictions. This is the last post in a four-part series looking at the Generic Ballot and its utility as an election predictor. You can read the first post in the series here

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The Republican Party’s structural electoral advantage in federal elections is well documented in liberal circles. Republicans won two of the last five presidential elections while losing the popular vote. The Senate — where states get equal representation — gives rural, Republican-leaning states undue voting power relative to their populations. Republicans have so heavily gerrymandered the House that Democrats are consistently underrepresented relative to their portion of the popular vote.

Our focus here at ESY is the House — questions about the presidency and Senate will have to wait. We’ll concentrate on the last claim: Do Democrats face a structural disadvantage in House elections?  To start, it’s important to understand two measures of bias in the House. We’ll then look at how these biases have come into play historically and, finally, how that relates to the generic ballot.

The Median House District
One way to measure bias in the House of Representatives is to compare the median House district’s electoral margin to the national popular vote. If you were to line up all the House districts from most Democratic to most Republican, the median House district would be the one directly in the middle. Number 218 out of 435. The district that would tip control of the House from one party to the other. The distance between this district’s margin and the national popular vote is one way to measure the House’s bias.

In 2018, Democrats led the House Popular Vote by 8.6%. In the median House district, California’s 10th, Democrat David Harder won by 4.5%.  If the whole nation voted 4.5% more Republican, Democrats would still have carried the popular vote by 4.1%, but lost CA-10 and, with it, control of the House. In this way, Republicans had a 4.1% structural advantage in the House in 2018.

David Wasserman of the Cook Political Report uses this measure to argue that Democrats have faced a disadvantage in the House since the 1960s.

The Seat Bonus
The other way to measure bias in the House bias is to measure each party’s “seat bonus”. A party’s seat bonus is the gap between their share of seats in the House and their share of the popular vote.

In a perfectly proportional system, a party that wins 53% of the vote would receive exactly 53% of the seats. The House, though, is decided by 435 individual elections rather than proportional allocation, making a perfectly proportional distribution of seats unlikely. In 2018, Democrats won 53% of the popular vote and won 235 of the House’s 435 seats, which translates to 54%. The Democratic seat bonus, therefore, is 1%.

This is perhaps a more intuitive way to measure the House’s bias. It also paints a more complex picture of the parties’ structural advantages and disadvantages in this legislative body. Unlike the “Median House District” measure, the “Seat Bonus”, over the years, has swung back and forth between the parties.

Tracking the “Seat Bonus”
The following graph shows Democratic and Republican overrepresentation in the House, measured by their proportion of seats minus their percentage in the national House popular vote, from 19721The 1972 redistricting was the first to take place under the Supreme Court’s “one person one vote” ruling which mandated districts of roughly equal proportion, making that election a natural starting point. to 2018. It’s a graph of each party’s “seat bonus”.2All data in the graph is rounded to the nearest 1%


Data: Brookings Vital Statistics on Congress

The graph shows three eras in the House. From 1972-1992 Democrats consistently benefited from a seat bonus while Republicans faced a heavy seat penalty. From 1994 – 2008, things were a bit more muddled, with Republicans and Democrats both usually benefitting from a seat bonus, but Republicans typically getting more of a bump. Lastly, from 2012-2016 Republicans got a strong seat bonus while Democrats faced a penalty. The most recent election 2018, seems to break this last era of Republican overrepresentation, but we will have to wait to see where the trendline goes in 2020 and after.   

These three eras line up almost perfectly with which party had control of the House. Democrats had majorities from 1972-1992, from 2006-2008, and again in 2018 while Republicans did from 1994-2004 and from 2010-2016. The party that won a majority in the House almost always received a bigger seat bonus. Out of 24 elections, only 1994 breaks the trend. And over these 24 elections, the party that won the House majority received an average 6% seat bonus. This bonus, however, has decreased from an average of 8% between 1972-1982 to 4% from 2008-2018.

The reason for the seat bonus deserves its own blog post and will be the focus next week. Some preliminary explanations:

1) Swingy seats are (proportionally) overrepresented. In 2018, there were 91 seats that fell in the range of +10 Republican to +10 Democratic. Since seats can range from +100R to +100D — a total range of 200 points — the 20-point range of +10R to +10D represents 10% of the total possible range. One might expect 10% of House seats to fall within this range. Instead, 91 seats (21% of all House districts) fell in this range. Because these close seats are overrepresented, a party will be disproportionately rewarded for marginal gains around 50% of the two-party vote.

2) Seats have different levels of elasticity — meaning they respond differently to changes in the national environment. According to FiveThirtyEight, for every change in 1% of the national popular vote, Michigan’s 5th District — the most elastic district in the nation — will move 1.24%. On the other side is Pennsylvania’s 3rd, which will only change .72%. Perhaps the swingy seats are also the most elastic, meaning that a party will be disproportionately rewarded for marginal gains around 50% of the two-party vote.

Again, these are just ideas. Next week we’ll dig into the data.

Below is chart similar to the one above, but this one uses the two-party popular vote, which excludes any votes for third parties.


Data: Brookings Vital Statistics on Congress

It looks almost identical to the first graph, with one big exception. In this graph, both party’s trendlines are consistently a few percentages lower.  When third party votes are included in the popular vote total, both Democrats and Republicans over-perform in House to a greater extent than when these votes are excluded. The reason for this is clear: third party votes rarely translate to real representation in the House. Third party votes increase the raw number of votes in the popular vote, meaning that Democrats and Republicans will receive a lower percentage of the total vote percentage. But because third party candidates almost never get elected, Democrats and Republicans do not see their overall representation in the House go down.

Tracking the Median House District
The Median House District measurement has shown a consistent bias in favor of Republicans for decades. Take a look at this graph charting the median seat in the House and Senate relative to the presidential popular vote. Every presidential year from 1968-2016 (excluding 1980), Republicans have had a two to six-point advantage. And that advantage has risen since the turn of the century, reaching about 5.5% in 2016.

This discrepancy comes from how Republican and Democrats are distributed among districts. Democrats are heavily concentrated in cities and urban areas; Republicans tend to be more spread out among rural, exurban and suburban districts. There are more districts with very high portions of Democratic voters than there are districts with very high portions of Republican voters. While party density makes it very easy for the individual seats, it also leads to a lot of wasted votes. Read my last post for more detail, but due to natural sorting and gerrymandering, Democrats waste more votes than Republicans. These wasted votes largely explain why the median House district is more Republican than the national popular vote. In 2018, Democrats won 180 seats by a 15% margin or greater while that number was just 126 for Republicans.

But…the Generic Ballot?
The Generic Ballot estimates the House popular vote which is used to project seat allocation between the parties. To understand the Generic Ballot’s utility at projecting seat allocation, it’s necessary to understand how well it predicts the House popular vote (which we covered in the first two pieces in this series) and how well that popular vote translates to seat allocation (which we covered in the last post and here).

According to FiveThirtyEight’s poll aggregator, Democrats lead the 2020 two-party Generic Ballot 53.7% to 46.3%, a 7.4% margin (as of July 13). This number is bound to change over the next year and a half. As 2020 approaches it will likely mirror the presidential election polls and in the meantime will track President Trump’s approval rating.

A 7.4% lead, though, would probably push Democrat’s past the Republican “Median House District” bias, giving them control of the House. Along with control of the House, Democrats would probably benefit from the “Seat Bonus” bias, giving them a greater than 53.7% (234 seats) share of House seats. Democrats didn’t get that “Seat Bonus” in 2018, winning about 8.6% in both the Popular Vote and seat allocation. However, as we saw from Republicans in 1994 and Democrats in 2006, it is common for a party to not receive a big bonus the first year that they re-take the House but then to see the bonus factor in the next election.

As we learned in the first post of this series, the Generic Ballot is pretty good measure of the national popular vote. It’s a good indicator of the national mood and predicts well how many House seats each party will win. We will end with two caveats to this. One: The Generic Ballot is much less reliable this far out from election day. Two: The House of Representatives is not decided by the national popular vote. It’s decided by 435 individual single-member districts with local factors and unique candidates. In this sense, there’s nothing at all general about House elections.

THE GENERIC BALLOT: SEAT ALLOCATION VS THE POPULAR VOTE (PART 1)

The 2020 elections are still 16 months away and yet pollsters are out in force, giving us just enough information to break out our crystal balls and make wildly irresponsible predictions. This is the third post in a four-part series looking at the Generic Ballot and its utility as an election predictor. You can read the first post in the series here

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The Generic Ballot is a poll question that aims to measure the national popular vote for the House of Representatives. Respondents are asked to choose between a nameless Republican and Democrat for Congress. Gallup asks it this way: “If the elections for Congress were being held today, which party’s candidate would you vote for in your congressional district — the Democratic Party’s candidate or the Republican Party’s candidate?”

Each party’s number of seats in the House of Representatives, however, is not determined by the national popular vote. A party that gets 45% of the popular vote will not always (or usually) receive 45% of seats in the House. Instead, we hold 435 individual elections, district by district. There are, therefore, two degrees of separation between the Generic Ballot and House seat allocation. The Generic Ballot predicts the national House popular vote which then can be used to estimate each party’s seat allocation.

How U.S. House Elections Work
The current conception of U.S. House elections — 435 individual districts with one representative each — is not mandated by the Constitution. Regarding seat apportionment among the states, the Constitution stipulates that states have House representation proportional to their population and that each state has at least one representative. As for elections, the Constitution says that only these representatives should be “chosen every second Year by the People of the several States.”

Instead, the Uniform Congressional District Act, a federal law passed in 1967, mandates the use of single member districts in all states with more than one representative except Hawaii and New Mexico.3These two states were given exceptions, allowing them to continue electing representatives at-large. Both states have since done away with this practice. Without this statute, a state could theoretically establish multi-winner elections, where all of a state’s voters choose from the same slate of candidates and the candidates with the most votes fill the number of open seats in order of votes received. If, for example, there were eight candidates running for three open statewide seats, the top three vote getters in the statewide election would fill those three seats. As of now, though, this is against federal law.

Maine did run ranked choice elections in 2018 for House and Senate, rather than traditional plurality elections. But even in this system, the state is split up into proportional districts according to population and each district gets one representative. With this caveat, the this single-member district, first past the post system of choosing representative dominates U.S. House elections. So that’s what we will focus on here.

Why Party Seat Allocation Differs From The Popular Vote
Single member districts mean that some votes will not be represented. The votes of Republicans in a heavily Democratic districts, Democrats in heavily Republican districts and third-party voters are essentially useless. And in close elections — say a candidate wins 51% to 49% — nearly half of the electorate’s votes go without representation. Unsurprisingly, on a national scale, this means party representation does not match the national popular vote.

A key concept is the ‘wasted vote’. There are two kinds of wasted votes. Type One is a vote that does not go the winner. So, in a 60-40 election, the 40% of votes that did not go to the winning candidates are Type One wasted votes. A Type Two wasted vote is any vote for the winning candidate over the threshold to win the election. It is essentially an additional vote that the candidate would have won without. In an election with a 50% winning threshold, any vote over that 50% mark is a Type Two wasted vote. One might think that, on a national level, the number of Republican and Democratic votes would balance out. There are two big reasons that this does not happen.

1) Natural Sorting
Democratic and Republican voters are not spread evenly across the country or within states. Democrats are concentrated in urban areas while Republicans are spread out over larger, more rural areas. When congressional districts are drawn, Democrats are often naturally placed into districts that are overwhelmingly Democratic due to their heavy concentration in cities and urban areas. This creates a lot of Type Two wasted votes. If an urban district is 85% Democratic, that 35% over the 50% mark are unnecessary for Democratic representation and wasted votes. On the other hand, Republicans tend to live in suburban, exurban and rural areas. They are more evenly dispersed around the country, making it rarer for a district to be overwhelmingly Republican. This distribution is more efficient for Republican voters, because if they live in more 60-40 districts than 85-15 districts, they have cast many fewer wasted votes.

2) Gerrymandering
Gerrymandering is the drawing of congressional districts to favor one party over another. Because state legislatures are responsible for drawing congressional districts, they often try to maximize their party’s federal representation.

The two methods used in gerrymandering are ‘packing’ and ‘cracking’. Both involve maximizing the opposite party’s number of wasted votes. Packing is drawing a small number of congressional districts that heavily overrepresent the opposition party’s voters, creating a lot of the Type Two wasted vote. Cracking is the opposite of packing — diffusing the opposition’s voters into districts so as to create Type I wasted votes.

Most gerrymanders are a combination of Packing and Cracking. Imagine a state that has 100 voters: 50 Republicans and 50 Democrats and five congressional seats of 20 people each. A Democratic legislature could draw the districts to look like this:

1) 20 Republicans
2) 7 Republicans + 12 Democrats
3) 7 Republicans + 12 Democrats
4) 8 Republicans + 13 Democrats
5) 8 Republicans + 13 Democrats

The Republican Packing in District 1 along with the Republican Cracking in Districts 2 – 5 allowed Democrats to win four out of five seats in a state that his half Republican.

Natural Sorting and Gerrymandering are the two biggest reasons that the national popular vote and seat allocation among the parties do not match. There are, of course, other reasons: third party votes, unequal district sizes, differing voter turnout in districts, etc. But these two are the biggest structural and geographic factors of our system that ‘distort’ House representation away from the popular vote. Now that we know what causes the gap between popular vote and House representation, we can look at how significant this gap has been in the past, how much it matters today, and which party tends to benefit from it. Next week: SEAT ALLOCATION VS THE POPULAR VOTE (PART 2)