30. January 2013 01:46
Our Microsoft Excel add-in, CDXZipStream, contains demographic data feeds based on data from the American Community Survey. The ACS is a survey performed by the U.S. Census Bureau which has replaced the old “long form” of the 10-year census. Please see our article ZIP Code Census Demographic Data in Microsoft Excel about our newest data feed, CDXACSZCTA, which provides for the first time comprehensive ACS data based on ZIP code.
Since the American Community Survey is performed annually, all the ACS data feeds in CDXZipStream are updated annually too. However, the smaller the geography, the longer the span of data required. For small geographies like census tract and ZCTA, the data must be aggregated over a five-year period to get statistically significant results; as of this writing the most recent set of five year data spans the years 2007 to 2011. Therefore, in these cases every annual update does need to incorporate some older data as well.
For some geographies, such as places (or cities), deciding what span of data to use is a balance between including as many geographies as possible versus using the most recent data. For CDXZipStream feeds, here are the data spans we use, along with the number of geographies for each feed:
State: 1-year data, 52 geographies (all states, including Washington D.C. and Puerto Rico)
CBSA’s*: 5-year data, 955 geographies (all CBSA’s)
Counties: 5-year data, 3,221 geographies (all counties)
Places (Cities): 3-year data, 3,128 geographies (only places with populations greater than 20,000)
ZCTA’s**: 5-year data, 33,120 geographies (all ZCTA’s)
All geographies were not included for places (cities), excluding those with populations of less than 20,000. In this case, it is generally a better choice to use ZCTA’s, which do cover a smaller population (averaging about 8,000) and is generally an easier index to use due to the availability of zip codes.
*CBSA’s (Core Based Statistical Areas) are the U.S. Census Bureau term for an urban area of at least 10,000 people.
**ZCTA’s (ZIP Code Tabulation Areas) are the U.S. Census Bureau version of a ZIP Code area. For more information please see our article What’s a ZCTA?
30. January 2013 01:35
Our Microsoft Excel add-in for zip code analysis, CDXZipStream, now includes a new feed that provides extensive demographic data based on ZIP Code Tabulation Areas. (ZCTA's are the U.S. Census Bureau version of ZIP codes.) This is the first time ZIP code-based data has been released from the American Community Survey. The ACS is an annual survey of about 3 million households performed by the U.S. Census Bureau. It has replaced the old "long form" version of the census, and includes many social, economic, and housing questions that were not part of the 2010 Census. The over 200 data fields in this feed cover:
- Individual Earnings
- Educational Attainment
- Household Size
- Household Income
- Housing Value and Rent
- Marital Status
- Mortgage Status
- School Enrollment
Click here if you would like to download a complete listing of the data feeds and fields provided in CDXZipStream, including the new feed listed under the name "CDXACSZCTA".
CDXZipStream includes a patented user interface that makes importing demographic data into Excel both fast and easy. For a short tutorial on how to use our newest data feed, please refer to the YouTube video ZIP Code Census Demographic Data in Microsoft Excel.
The new feed is available with the Premium ACS version of CDXZipStream, which includes all demographic data feeds and data analysis functions. Pricing for all versions of CDXZipStream is available on our pricing page. If you already have this version, the new feed is included in the most recent Premium ZIP Code data update. Other current users of CDXZipStream can upgrade to this version by logging into their CDXTech.com account and selecting “Upgrade Licenses”. In both cases, be sure to also get the newest 11.2.2 (free) update of CDXZipStream, available by clicking on the "License Information and Software Updates" button on the toolbar, then selecting "Software Updates".
21. June 2012 22:45
Stats in Action Video: Target
This is not the typical forum for addressing political issues, but one of the major sources of demographic data for our Excel add-in, CDXZipStream, is on the congressional chopping block. The American Community Survey (ACS) is an annual survey performed by the U.S. Census Bureau, and is a significant source of social, economic, and housing data for government, business, and non-profits. As of May 9, 2012, the House of Representatives voted to remove funding for the ACS, and although the Senate is unlikely to do the same, a compromise measure may radically change the current survey.
The ACS used to be called the "long form" of the ten-year census that was sent to only selected households. The long form was abolished after the 2000 Census, and became an annual survey so the data would be more timely and be able to more effectively direct government budgeting.
Both cost and constitutionality seem to be issues driving the de-funding, although some form of the survey has been in place since the 1800’s and constitutionality has previously been upheld by the courts. There are also concerns about the possible intrusive nature of the survey questions.
“This is a program that intrudes on people’s lives, just like the Environmental Protection Agency or the bank regulators,” said Daniel Webster, a first-term Republican congressman who sponsored the amendment that removed it from the House budget.
A major concern is that a compromise measure with the Senate will make the ACS a voluntary survey and result in much lower participation rates. Ironically, this means costs go up as more census workers are required to go into the field to boost participation; if participation does not reach levels required for statistical significance, the data is effectively useless.
Private companies, business and industry groups, academia, and economic development organizations have all voiced opposition to the Webster ammendment. For example, the U.S. Chamber of Commerce states the ACS data allows its users “to make informed decisions regarding strategic development opportunities that strengthen our communities, provide for the efficient and effective delivery of goods and services, create jobs, and ultimately drive economic growth.” To see how a company like Target uses the ACS, please click on the video shown at the top of this post.
To voice your opinion on the American Community Survey, please consider contacting your U.S. Senator or Representative. Contact resources are available at the following links:
U.S. House of Representatives
8. February 2011 19:17
Data from the U.S. Census Bureau is an indispensible source of demographic information that helps businesses, non-profits, and even the smallest mom-and-pop store plan, market, and ultimately reach their target audience. But there are limitations to the data, particularly for smaller geographies, that should be considered before making any critical demographics-related decisions.
Since participation rates for census surveys are never 100%, there will always be some error associated with demographics estimates. For example, the American Community Survey samples about 2% of American households every year, and the accuracy of the estimates can vary significantly, especially for geographic areas where populations are small and sampling error can be large. Here are some results from the latest 5-year data set from the ACS covering the years 2005-2009:
The error results for the American Community Survey are all for 90% margin of error, meaning that there is 90% confidence that the true result lies within the margin of error around the estimate. For instance, for Albany County, there is 90% confidence that the median income is $55,350 plus or minus $1,061; this means the actual 90% confidence range is $54,289 - $56,411. Even with this level of error, however, the median income estimates for Albany County, Albany city, and Census Tract 2 are significantly different from a statistical point of view, since there is no overlap when including the margin of error for each estimate.
In the case below, involving all small census tract geographies, the picture is not so clear:
Since the margin of error is so large for Census Tract 4.01, we cannot be confident that the true median income is statistically different from Census Tract 1. The estimate ranges, including the margin of error, overlap for Census Tracts 1 and 4.01, even though the estimate values ($37,619 versus $62,039) are quite different. We can say with confidence, however, that the median income for Census Tract 2 is statistically different from Census Tract 4.01 since the estimate ranges do not overlap. It certainly helps in this case that the margin of error for Census tract 2 is relatively small for this geography.
It's easy to cherry-pick data like this to show how the margin of error effects how we interpret the results, but the fact remains that survey error can be an important part of data interpretation particularly for cases where the error is large. When important decisions need to be made based on demographics, margin of error should always be part of the analysis.
11. January 2011 03:03
In a previous post we talked about how the results of the 5-year (2005-2009) American Community Survey, released in December 2010, would provide demographics down to the zip code level for the first time. Unfortunately, the Census Bureau did not provide zip code data with the current data release, and won't be including it for some time, at least until 2012-2013.
Zip codes, as defined by the U.S. Postal Service, are not actually a "geography" included in Census Bureau surveys. Realizing there is significant interest in zip code demographics, the Census Bureau did provide Census 2000 data by "ZCTA" (Zip Code Tabulation Area), which required grouping data from small census "blocks" in order to approximate an actual zip code. You can see how ZCTA's and zip codes compare in these example maps of Washington state. (Also see our previous blog post with a more detailed ZCTA description.)
Since zip codes frequently change in definition and area, the Census Bureau must now update ten-year old ZCTA definitions. This is a complex task that was not completed in time for this first 5-year data release. In the meantime, we at CDX Technologies are evaluating other options for providing ACS data in smaller geographies. (We currently provide state, county, CBSA (Core-Based Statistical Area) and city data in our CDXZipStream ACS data feed.) We'll keep you posted as our work proceeds.
29. September 2010 06:49
We've had a number of questions from our clients as to why the CDXZipStream demographic feed from the American Community Survey doesn't include data down to the zip code level. It does include data for larger geographies like state, county, and "places" (the Census Bureau's version of city, town, borough, etc.) but zip code data seems to be a glaring omission.
To understand this, we need to talk a little bit about how the American Community Survey (ACS) works. The ACS is a survey that has been performed by the U.S. Census Bureau every year since 2005; it has replaced the old "long form" that used to be part of the decennial (10-year) census. Starting in 2010, the decennial census now only consists of the "short form" that covers basic questions about age, gender, race, and household size. The more interesting demographic data such as income, educational attainment, and other socioeconomic factors are now being obtained exclusively through the ACS.
Each year the ACS surveys about 3 million U.S. households, and in order to get statistically valid demographics for smaller geographies like zip codes, the data must be combined over a five year period – there just isn't enough data for a single year to get an accurate picture for a zip code. In fact, one year data is applicable only to geographies with a population of 65,000 or more, and the three year combined data included in CDXZipStream is applicable to geographies of 20,000 or more. Since the ACS formally started in 2005, five year data (covering the period 2005 through 2009) will be released for the first time in early December 2010; it will be available in CDXZipStream within two weeks after its release.
So what's the big deal? The real advantage of the annual American Community Survey is that it will show a true moving picture of American demographics that could never be provided by the 10 year "snapshot" of the decennial census. Zip code demographics from here on out will be updated annually using data from the last five surveys, and trends can be measured using real data instead of relying on error-prone models based on extrapolations of old data. So stay tuned ... we expect demographics by zip code will be available in CDXZipStream by the end of 2010.
20. September 2010 19:16
The U.S. Census Bureau expects to release the first major data compilation from the 2010 Census during the summer of 2011. We will include this data in the CDXZipStream Premium and Premium ACS versions approximately two weeks after its release.
However, beyond the 2010 Census, there's another important milestone coming up: in December 2010 the Census Bureau will release for the first time 5-year estimates from the American Community Survey, which will include data down to the zip code level covering the years 2005-2009. This survey (which has replaced the old "long form" of the ten year census) has population, race, gender and age data like the 2010 Census, but also includes education, socioeconomic, and housing information that is not included in the 2010 Census. It will be updated annually and will be much more current than previous census data obtained every 10 years. We will include the American Community Survey 5-year data in the CDXZipStream Premium ACS version approximately two weeks after its release.
The five-year American Community Survey data represents a major shift in how demographics is collected, and we'll be discussing this data in more detail as we get closer to the December 2010 issuing date. Check back later for more postings ...