Wednesday, December 29, 2010

Big Five Personality Traits, Outliers and Per Capita Income in the U.S.

I went back and played with the data from that survey of Big Five personality traits by state (the OCEAN traits) and the NYT has a neat gadget; data below from there. Per capita income data comes from the Census. Automatically you start thinking about correlations between the Big Five and other things like income.

- Big Five traits and per capita income.
- Interestingly the strongest correlation at the state level both in terms of goodness of fit and slope (strength of influence) in a linear model is an inverse one with conscientiousness. Want to make money? Be lazy! Who knows the causal relationship here if any, so I won't hand-wave. With an R^2 of 0.2646, the regression says the state's per capita rises $236.87 for every rank lower you go on the conscientiousness scale. You also get money for being disagreeable ($221.87 for every rank the state drops, R^2 = 0.2321), although you also get money for being open-minded ($182, R^2=0.1566). This is probably largely the Northeast talking, although it might be interesting to look at the correlation between education and openness.

- Combinations of Big Five traits by state. If you do scatterplots with each of the Big Five characteristics against the others, several states appear repeatedly as outliers at the "corners" of the scatter - DC is one and Alaska is another. The whole reason that the study which initially generated this data is interesting is because it shows that there actually is a geographical difference in personality types (whether that's because of memes or genes is another question entirely). But it stands to reason that if gene and/or culture flow can explain this, then we should see outliers at the geographical extremities. It also stands to reason that the outliers on the coasts won't necessarily be outliers in the same way. While the map of openness does bear a similarity to the Red/Blue presidential voting distribution, there is no other obvious correlation between other characteristics or states.

So I looked at the coastal states (those with a saltwater port) against the non-coastal states, excluding Hawaii and Alaska. If geographic extremes correlate with personality type "outliers", then the saltwater states (which are farther from each other) should also be more dissimilar to each other than the interior states. By my count there are 26 interior and 23 saltwater states, so all other things being equal, the saltwater states should look more similar to each other, since there are fewer of them.

Indeed, the standard deviations for 3 of the 5 big 5 are smaller for the interior. They're the same for the other 2. As far as the averages, the interior states are more extraverted, agreeable and conscientious than the coastal states. (Those first two are consistently a shock to me.) The noncoastal states are on average less neurotic and less open to new experiences and ideas.

- Combinations of Big Five traits by region. If you do scatterplots with combinations of Big Five scores by region, then the Northeast (DC to Maine) is frequently an outlier (conscientiousness vs neurotic, conscientiousness vs openness, consciousness vs extraversion; more on this in a bit). The contiguous Pacific states are a major outlier on agreeableness vs openness; otherwise they land near the other states in and west of the Rockies. The Frontier Strip lands with the Midwest and the Bad Stripe tends to sort with the South, except that it's much less open than other Southern states.

- Per capita income distribution and average, coastal vs. non-coastal. It's also worth pointing out that the per capita incomes of non-coastal states were a) more similar to each other than the coastal states' were and b) on average lower, by $5,128. This is not surprising, as land-locked countries also have lower per capitas than those with coastline. 2/3 of all Alpha and Beta cities are on saltwater (or a river delta leading into saltwater), so, par for the course.

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