ACS vs. CPS vs. PEP vs. Census

Question

I am very new to census analysis/survey analysis so please forgive my ignorance.

I am interested in MOST data/information about the U.S.A. population. Demographic information like breakdown by age, race, sex as well as things like health-care coverage, income, poverty levels, unemployment rates, etc. I'm also interested in these things on a national, state, and substate level.

And then I'm also interested in these values on a year to year basis to see how the United States has changed.

For now I think I am mostly interested in the aggregated tables and summaries for these values not so much in the microdata. But I suppose this could change in the future especially as I grow more comfortable and learn more about how to properly analyze survey data.

To me it's very chaotic and hard to get a sense of the landscape for accessing this data as it is contained in a variety of different surveys behind a variety of different APIs and search tools.

In any case if anyone could provide any tools or suggestions for helping navigate the myriad amount of resources on the topic of the population of the United States, that'd be great.

For now, my real question is... if I wanted to get a sense of how the U.S.A. population is changing year to year in regards to age, sex, and race, should I be using CPS (Current Population Survey) data, ACS (American Community Survey) data, Decennial census data, or PEP (Population Estimates Program) data? And then additionally, which should I be using for which geographic entities so to speak? I know this question is broad and probably will depend on the specifics, but any general guidance in this department would be helpful.

EDIT: I am interested in the totals for these populations not just the percentages if that makes sense.

Answer 1

Geography is often a key factor in determining which dataset you'll use. Are you looking for national numbers? States? Counties? In general:

If you want annual data, only need the basics (age, gender, race) then the Population Estimates Program data is the simplest to use. The data is published by state, county, and metropolitan areas, and also for large municipalities. Like all of the census datasets it's available via the American Factfinder and the census APIs, but since it's relatively small they also provide simple csv files you can download. Each sheet will provide numbers from 2010 to the latest year, and you can go back and get the previous decade in older sets of files. Right now data for all areas for 2016 is available. Data for 2017 has just been released for states but isn't available for other areas yet. The csvs are available directly from the program website:

https://www.census.gov/programs-surveys/popest.html

The American Community Survey (ACS) is better if you need detailed socio-economic summary data beyond the basics of age, race, or gender, or if you need additional geographies - you can get states and counties but also smaller areas like census tracts and ZIP Codes. So if you need data on poverty, health insurance, unemployment, etc then this would be the source you need. For larger geographies that have more than 65k people you can get annual data, but for smaller areas the data are published as 5-year averages. Each estimate is published at a 90% confidence interval with a margin of error; in some cases you may need to use the 5-year averages even for larger areas if the margins of error for the estimates you're using are prohibitively large.

It's challenging to gather and analyze ACS data on an annual basis, partly because the API and American Factfinder are designed to deliver data for one particular release at a time and not multiple years. For the 5-year averages it's only appropriate to compare sets of years that don't have overlap; 2012-2016 vs 2007-2011 would be appropriate.

Some alternatives - the NHGIS https://www.nhgis.org/ provides some historical comparison tables, but is intended for doing longer-term research that covers many decades. The ACS came into existence in 2005; prior to that, detailed socio-economic data was collected in each ten-year census. The Missouri Census Data Center http://mcdc.missouri.edu/ has an ACS Trends application (in the toolbar on the right) that lets you pull together several years of ACS data. They also provide descriptive summaries of the different datasets which might be useful.

We have a few tutorials that we wrote in our lab that cover the basics of navigating the American Factfinder. There's also some explanation of the different datasets and geographies. https://www.baruch.cuny.edu/confluence/display/geoportal/Census+Tutorials

Lastly - the CPS is typically used if you need national estimates on an annual or monthly basis, or if you need or want microdata. https://usa.ipums.org/usa/.

Answer 2

NHANES- National Health and Nutrition Examination surveys

If you are into R, You could install the NHANES package, it gives you data on 10000 Americans, 75 attributes, from 2009-2012 with adjusted weighting

Why adjusted weighting? - From the documentation:

"The NHANES target population is "the non-institutionalized civilian resident population of the United States". NHANES, (American National Health and Nutrition Examination surveys), use complex survey designs (see http://www.cdc.gov/nchs/data/series/sr_02/sr02_162.pdf) that oversample certain subpopulations like racial minorities. Naive analysis of the original NHANES data can lead to mistaken conclusions. The percentages of people from each racial group in the data, for example, are quite different from the way they are in the population.

NHANES and NHANESraw each include 75 variables available for the 2009-2010 and 2011-2012 sample years. NHANESraw has 20,293 observations of these variables plus four additional variables that describe that sample weighting scheme employed. NHANES contains 10,000 rows of data resampled from NHANESraw to undo these oversampling effects. NHANES can be treated, for educational purposes, as if it were a simple random sample from the American population.