Correlations that get at why big cities lean toward Democrats

Richard Florida discusses several reasons, based on correlations, why big cities now so clearly lean toward the Democratic party:

Density played a key role in the metro vote. (To capture it we use a measure we of population-based density, which accounts for the concentration of people in metro). The average Obama metro was more than twice as dense as the average Romney metro, 412 versus 193 people per square mile. With a correlation of .50, density was an even bigger factor than population (where the correlation is .34). The reverse pattern holds for the share of Romney votes; the negative correlation for density (-.51) was significantly higher than that for population (-.33)…

The chart below plots the relationship between a metro’s share of college grads and its share of Obama votes. The line slopes steeply upward showing how the share of Obama votes increase alongside metro density. The share of college grads in a metro is positively correlated with the share of Obama votes (.42) and negatively with the share of Romney votes (-.44)…

The chart above shows the relationship between the share of the creative class and the share of Obama votes across metro areas. The line slopes steeply upward, indicating a considerable positive relationship. The share of creative class workers is positively correlated with the share of Obama votes (.40) and negatively with the share of Romney votes (-.41)…

Republicans may still be the party of the rich, but most of the country’s more-affluent metros lined up squarely in the Obama camp. The correlation between the average wages and salaries of metros and the share of Obama votes is positive (.50) and it is negative for Romney votes (-.51). This makes sense too, as larger metros have greater concentrations of knowledge-based talent and industries and are wealthier to begin with. (The associations we find are even more substantial for metros with more than one million people, with the correlations increasing to .71 for Obama and -.72 for Romney.) This follows the “Red State, Blue State, Rich State, Poor State” pattern identified by Andrew Gelman of Columbia University, who infamously found that while rich voters continue to trend Republican, rich states trend Democratic.

Florida argues this is evidence of class-based differences in American life, specifically, differences between the creative class and those in knowledge industries compared to the rest of the United States.

However, this raises a few questions:

1. The analysis here seems to be done across metropolitan areas while some of these voting patterns break down as we compare cities versus suburbs. For example, there are those who suggest it is really about cities and inner-ring suburbs that vote Democratic while more further flung suburbs and exurbs vote Republican. See earlier posts about the analysis of Joel Kotkin – here and here.

2. Making claims with correlations with tricky. Florida acknowledges this before he rolls out the analysis: “As usual, I point out that correlation points to associations between variables only, not causation.” But, then why stop the analysis at correlations here? Looking at the relationships just between two variables at a time ignores the complex relationships between factors like race, class, location, jobs, and more. Why not quickly run some regressions?

3. If this analysis is correct (and we need more in-depth analysis to check), why are Republicans so bad at appealing to the creative class?

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