By Frank Bass
The U.S. Census Bureau puts together a wealth of health-related information from its American Community Survey and decennial Census. You can track down ages, types of disabilities, poverty status and even health insurance for most places. While Census data has a well-deserved reputation for complexity that often requires advanced computer skills, you can find useful information with just a few mouse clicks – if you know where to look.
The first thing to understand is when to use data from the American Community Survey (ACS), which is conducted annually, and when to use data from the decennial Census. Here’s how it works:
∙ If the area you’re examining has 20,000 or more people, you can use the three-year average ACS numbers.
∙ On Dec. 14, 2010, the Bureau will release the five-year ACS numbers for Census tracts and block groups, which generally have fewer than 5,000 people. The five-year estimates are based on 60 months of collected data from all areas (the previously released three-year estimates did not include Census tracts and block groups, which generally have fewer than 5,000 people). The data are considered to to be the most reliable because of the large sample size but are less current than the three-year estimates.
∙ If you can’t use ACS data, you’ll have to use the 2000 Census data until mid-2011, when the next decennial Census data are released. Those numbers will cover all U.S. geographies down to a tract level.
- Using the ACS: Ages
- Using the ACS: Poverty
- Using the ACS: Health Insurance
- Using the ACS: Disability
- Using the Decennial Census: Ages, Disability, Poverty Status
- Finding More Information: American Community Survey
- Finding More Information: Decennial Census
Using the American Community Survey: Ages
The best place to start is the Census Bureau’s FactFinder tool at http://factfinder.census.gov. In the examples below, the screen shots show the ACS three-year data. As of Dec. 14, 2010, you should be able to choose the ACS five-year data.
We’ll start with a pair of simple questions: How many children under the age of 5 in Springfield, Mass.? We’ll begin by clicking on the “get data” link in the American Community Survey section, underneath “Getting Detailed Data” in the center frame:
This will take us to the main ACS query page. We’ll select the “Detailed Tables” link:
This takes us to the geography selection page:
We’ll start by selecting place. An important note: Some cities are places, and some are county subdivisions. Some cities – especially in places like Virginia and New Jersey – are both. Know whether you’re dealing with a city or a town (county subdivision). The screen should look like this now:
Select “Massachusetts” as the state, “Springfield” as the place, then add it to the “Current Geography Selections.”
We’ll add Table B01001, Sex by Age:
When we click on the “Show Result” button, we get this:
When we add the male and female figures, we get 11,634 children under the age of 5 years old. Divide by the total population (149,586), and we see that 7.7 percent of the city’s residents are younger than 5.
Using the American Community Survey: Poverty
Poverty and poor health are often linked. Where poor people live, there’s likely poor health. Poor people have more chronic illnesses, greater complications, and they use the health care system much more than healthy people.
So, where to find poverty?
Let’s see which of the five largest cities in Massachusetts – Boston, Worcester, Springfield, Lowell and Cambridge – has the highest poverty rate. We’ll go back FactFinder’s main page:
We’ll select “Detailed Tables,” and select “Place” as the geography, “Massachusetts” as the state, and Boston, Cambridge, Lowell, Springfield and Worcester as the places:
We’ll select Table B17001, “Poverty Status in the Past 12 Months by Sex by Age.”
Here are the results:
Finally, we’ll do the math, dividing the number of poor people by the total population. We’ll find that Springfield, with a 27.1 percent poverty rate, is the poorest big city among the top five. Boston is second, with a 19.6 percent poverty rate. Both Lowell and Worcester have a 17.5 percent poverty rate, and Cambridge has 15.3 percent of its residents in poverty.
We could, of course, add up all the categories for people under 18 years old and calculate child poverty. We can also look at poverty for different races. But for purposes of this example, if we wanted to do a story about urban health problems in Massachusetts, we’d want to start talking to people in Springfield.
Using the American Community Survey: Health Insurance
The Census Bureau included health insurance status in the American Community Survey for the first time in 2009. Before the ACS estimates, the only source of health insurance data was the Current Population Survey, also conducted by the Census Bureau. The ACS estimate, however, will be more reliable as time passes since the sample size is 25 times larger.
We’ll start at the main ACS page. Because of sample size issues, though, we have to use one-year estimates, which only cover places with 65,000 or more people:
(Note: After Dec. 14, 2010, you should be able to use the five-year numbers.)
We’ll start by selecting five California counties from the query page:
We’ll select Table B027001:
Here are the results:
When we do the math, we see that Los Angeles County has the highest percentage of uninsured people, with more than 22 percent. San Francisco County is at the other end of the spectrum, with 10.4 percent. We can also look at the percentage of uninsured children, with similar results; Los Angeles is first, with nearly 14 percent, and San Francisco only has 4.3 percent of its children uninsured.
Using the American Community Survey: Disability
Likewise, the Census Bureau doesn’t yet have enough data to compile disability figures for places that have fewer than 65,000 residents. In general, the Census Bureau defines a disability as “a long-lasting physical, mental, or emotional condition. This condition can make it difficult for a person to do activities such as walking, climbing stairs, dressing, bathing, learning, or remembering. This condition can also impede a person from being able to go outside the home alone or to work at a job or business.” The Census Bureau has more guidance here:
http://www.census.gov/hhes/www/disability/disab_defn.html#ACS
We’ll start at the main ACS page:
We’ll select “Detailed Tables” and choose the five California counties:
Next, we’ll select Table B18101, “Sex by Age by Disability Status.”
When we do the math, we find that Sacramento County has the highest rate of people with a disability, 13.8 percent. Orange County has the lowest, with 7.7 percent.
Using the Decennial Census: Ages, Disability, Poverty Status
If you’re trying to find out information about a place that has fewer than 20,000 people, you’re going to have to use the 2000 Census – at least, until roughly summer 2011. You also can’t get health insurance figures, since that question isn’t part of the decennial Census. That’s the bad news. The good news is that the 2000 Census has several thousand more geographic locations than the American Community Survey.
Let’s use our first example, finding out how many children live in Springfield, Mass. We’ll go to the main Census data page at http://factfinder.census.gov
Next, we’ll select the “get data” link from the “Decennial Census” section. When we click on that link, we’re taken to this page:
We can use just about any one of the summary file selections to find information on age, but we’ll use Summary File 3 here. It’s the most comprehensive summary file from the 2000 Census long form, containing a fair amount of information that’s duplicated from earlier summary files. We’ll select “Detailed Tables.”
Let’s do something different and see which Census tract in Windham County, Vt., has the highest percentage of children younger than 5. We’ll select “Census tract” from the type of geography, then “Vermont,” then “Windham County,” then “All Census tracts.”
We’ll select Table P8, Sex by Age:
When we click “Show Result,” we get the following:
There’s a bit of a problem here; the sheet only shows the first 10 tracts. You’ll have to click on the “Next” link to add them all up. When you do, you’ll find that Census Tract 9674 has the most children under the age of 5, with 6.7 percent; Census Tract 9680 has only 4.2 percent of its population under the age of 5.
Now, there’s a really big problem. Where is Census Tract 9674? Census tracts just aren’t a common type of geography. You never hear about them, mostly because we translate the unit into something a little more reader-friendly, such as “neighborhood” or “area.” There are roughly 75,000 Census tracts in the United States; they average about 3,500 people each.
We’ll go back to the main Census page:
Next, we’ll select Summary File 1 and click on the “Thematic Maps” flyout link:
We fill out the screen here:
When we click on the “Map It” button, we should get a decent map of the area:
If you need something even more specific, you can go to a web site operated by the Census Bureau at http://ftp2.census.gov/plmap/pl_trt/
For the Vermont example, we’d open up the Vermont directory:
We’d open the Windham subdirectory:
Fortunately, there’s only one PDF file. In many larger tracts, there are dozens, and you’ve got to sort through them to locate a specific tract. But here’s another map of Census Tract 9674:
Finding More Information: American Community Survey
This primer doesn’t even begin to answer all the questions that will come up when you’re looking at Census data. Why is a place listed twice? What exactly is a service-connected disability? Does health insurance coverage include Medicare and Medicaid? What about military insurance? Do prisoners count in the Census?
Fortunately, the American Community Survey has a fairly extensive network of support pages. Here’s the main page:
The first tab, “About the ACS,” contains useful information about specific questions, such as health insurance and service-connected disabilities.
The next section, “Access the Data,” includes very important information about new questions, geographic areas covered, and guidelines for comparing data from year to year.
The “How to Use the Data” section includes useful information on geography and definitions:
Finding More Information: The 2000 Census
As complicated as the American Community Survey can be, the decennial Census is the motherlode of complex data. A good overview of the Census and process can downloaded here:
http://www.census.gov/mso/www/c2000basics/00Basics.pdf
The overview is about as basic as it gets – which, given the Census, isn’t very basic. To really understand the definitions and geographies, you’ll need to read quite a bit of the technical document. And the technical documentation for Summary File 3 alone – the source of quite a bit of health-related information from the 2000 Census – is 1,269 pages. It’s a PDF that can be downloaded from here:
http://www.census.gov/prod/cen2000/doc/sf3.pdf
Finally, we’d recommend going through the 2000 Census main gateway at http://www.census.gov/main/www/cen2000.html:
Frank Bass is enterprise reporter at Bloomberg News. He was the director of computer investigations at The Associated Press, where he generated data-related stories and provided training in computer-assisted reporting techniques to reporters on four continents and more than 50 domestic bureaus. He is the author of the Associated Press Guide to Internet Research and Reporting.
