Mapping the ethnic and racial diversity

Andrey Kamenov, Ph.D. Probability and Statistics

It’s relatively well-known by now that the population of the United States is becoming more diverse each year. A few weeks ago, the U.S. Census Bureau released its 2016 population estimates. Let’s see what the most recent data says about the population’s racial and ethnic backgrounds.

A common way to quantify a population’s diversity is called the Simpson Index (also referred to as the Herfindahl–Hirschman index). Without getting into details, we can describe the index as the probability that two randomly-chosen people belong to the same racial and ethnic group.

Which racial and ethnic groups are we talking about? We actually follow the classification used by the U.S Census Bureau. It distinguishes five different racial groups, while counting all people who listed two or more races as a separate sixth group. Further differentiating people based on their Hispanic or non-Hispanic origin leaves us with 12 possible combinations.

Now, in some of the southern states with higher percentages of Hispanic populations differences in ethnic background account for a large part of the entire index. So, below you can find two different maps — one shows the compound index (racial and ethnic), while the other shows only racial diversity.

Compound & racial diversity in the U.S, by county

The Census Bureau's population estimate gives us another characteristic to study: the respondent's age. Here's how the diversity (on the scale of the entire country) changes in different age groups. Again, the charts below show both the compound and racial diversity.

Compound & racial diversity in the U.S., by age group

As you can see, the diversity strictly decreases with age; while two toddlers have nearly a 70 percent chance to be of either different races or national origins, the number dips below 40 percent for the elderly. Another notable trend is that the decrease in diversity begins to show most prominently after the age of 40.


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About Andrey Kamenov

Andrey Kamenov, Ph.D. Probability and Statistics

Andrey Kamenov is a data scientist working for Advameg Inc. His background includes teaching statistics, stochastic processes and financial mathematics in Moscow State University and working for a hedge fund. His academic interests range from statistical data analysis to optimal stopping theory. Andrey also enjoys his hobbies of photography, reading and powerlifting.

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