The Incredible Statistical Difference between Democrats and Republicans

by Benjamin Studebaker

Lately I’ve been reading a book by Larry Bartels entitled Unequal Democracy: The Politics of the New Gilded AgeBartels has conducted an incredible study that produced statistical outcomes I was not, to this point, aware of. Given the amount of time and energy I devote to politics, it stands to reason that the general public is not aware of them either, and it is absolutely imperative that, so long as this remains a democracy, every citizen be made aware of what Bartels has found, so I set out today to communicate these figures to whoever might be out there reading, in the hope that perhaps they will be shared more widely.

Here’s what Bartels did–he took US economic data from 1948-2005 and separated it out by which political party controlled the white house. Truman, Kennedy, Johnson, Carter, Clinton go to the democrats, Eisenhower, Nixon, Ford, Reagan, and the two Bushes go to the republicans. He compared the economic numbers under the democratic presidents to the numbers under the republican presidents. He included a one-year lag under the assumption that policies take some time to go into effect–the first year of Reagan’s presidency counts as part of Carter’s, the first of Carter’s is Ford’s, and so on. Bartels went into this study with non-partisan scientific intentions. He claims to have not voted since 1984, when he voted for Reagan. Nevertheless, he found stunning differences, far too strong statistically to be driven by mere chance–it held true even if any one or two presidents were excluded from the study.

A few of Bartels’ graphs have been posted elsewhere online in years past, but some are nowhere to be found, so I have reconstructed them on excel. This first figure compares real (inflation-adjusted) income growth for several different income percentiles (the 20th, 40th, 60th, 80th, and 95th) under presidents of the two parties:

Income Growth Party Comparison

This reveals two spectacular differences between the parties, one of which most of us likely suspected but could not prove for sure, the other  likely violates the expectations even of many on the American left:

  1. Under democratic presidents, economic inequality decreases slightly. Under republican presidents, economic inequality rises rapidly.
  2. Democratic presidents produce higher average annual income growth for all portions of the population than do republicans–even the 95th percentile experiences higher income growth under democrats.

It’s possible that there is some portion of the population even more affluent than the 95th percentile (the top 1%, 0.1%, or .01%?) that experiences higher income growth under republicans, but this nonetheless suggests that even someone in the top 5%, with a personal income of $100,000 or household income of about $170,000, will prosper on average slightly more under a democrat than he would under a republican. If citizens voted for the party that put more money into their pockets, at least 95% of them would vote democratic every time.

Many commentators believe that rising inequality is structural, that certain rare or difficult to acquire skills are currently prized by the economy, and that this is the reason inequality has risen post-1980. Bartels’ numbers directly challenge this claim–if inequality were structural, we would expect to see it grow at roughly the same rate regardless of party politics. Instead, we see a vast difference between the two parties–republicans expand inequality at breakneck pace and democrats shrink it slightly.

In his book, Bartels goes to great lengths to verify his result. He adjusts for a bevy of possible noise-making variables–unemployment, inflation, oil prices, labor force participation, and so on. If readers doubt the veracity of the figures, I encourage them to read his book in which he discusses his methodology in much greater detail than I can here.

Republicans could respond to these numbers by arguing that their presidents are forced to embrace contractionary policy in order to combat the runaway inflation they believe democrats permit. However, Bartels does not merely compare incomes–he also looks at the difference in the unemployment rate, inflation, and GNP growth, and those results are just as stunning:

Economic Indicators Party Comparison

This reveals that while democrats keep unemployment rates significantly lower than do republicans and maintain much higher average GNP growth rates, the republican advantage in inflation is statistically insubstantial. This suggests that there is no substantive economic advantage to having a republican president at all.

However, despite this, democrats won presidential elections only  40% of the time during the 1948-2005 period (they went 6-9, in sports terms). Why might this be? Bartels observes that republicans regularly generate much higher income growth rates during election years than they produce the rest of the time:

Economic Manipulation Republicans

Amazingly, in a non-election year, an American in the 20th percentile actually sees his income shrink on average under a republican president, yet in an election year, his income will grow as much as the income of someone in the 95th percentile does in an ordinary year.

By contrast, democrats have consistently failed to manipulate the voters in this way, actually performing worse, across the board, in election years:

Economic Underperformance in Election Years Democrats

This is very odd. We know democrats know how to grow the economy more effectively than republicans–they get better numbers most of the time. Yet, during an election year, republicans can spontaneously turn it on while democrats run into some kind of obstacle. There are a few possibilities: 

  1. Ignorance–republicans are bumblers, but they have the support of some plutocracy (the top 1%, 0.1%, or 0.01%?) that is in charge of a sufficiently large part of the American economy such that they can manipulate wage growth figures to make republicans look good during election years and make democrats look bad, especially to potential affluent donors who actually experience a decline in real incomes during democratic election years.
  2. Malevolence–the republicans deliberately grow the economy slowly for some reason (perhaps inflation? But we’ve already established that they don’t fight inflation effectively). In election years, they deliberately change policies, producing higher growth figures temporarily in order to win. When in opposition, they use congressional influence to sabotage the democrats’ chances.

In either case, the American public is being played–the question is by whom (the very rich, or republican politicians?). If republican politicians are doing this, it unveils a shocking asymmetry–democrats either do not engage in this tactic at all, or do so with spectacular incompetence. I think it is more likely that republican politicians are bumblers aided by the machinations of super-rich backers, though it’s possible that both forces are to some degree in play. 

Given this information, it appears masochistic to support republican presidential campaigns, yet inevitably, large portions of the population continue to be taken in by the illusions put in front of them during election years. So long as the United States remains a democracy, it is imperative that as many of them be made aware of the fact that they are being manipulated in this way as possible. If you agree, please share this piece.


I thought about this a little more and decided that the two explanations for the gap in election year performance between the parties I offered here were flawed. I have written a more detailed explanation that is more attentive to the contingent qualities of the various elections in Bartels’ data set. It can be read here.