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Using ACS for Complex Data Dives

David
over 4 years ago

Hello,

I'm trying to determine the best way to do more complex queries using ACS. It may be that my better answer is PUMS or another method, in which case, please let me know! My current director is leaving, and she's not familiar with the changes in the system. So, I reached out to Census, and they suggested asking here or trying PUMS.

I'm looking for data, especially local data (ACS will sort by place to the cities I'm looking for just fine), but I want to use more nested variables. Looking up places for one or two characteristics works fine, but I feel like I'm just taking shots in the dark at how to use the search to get, for example,

   % of total households that are female-led, foreign-born, below the poverty threshold, with children under 5, in (selected cities/places)

     (then the same for citizen vs non-citizen, and the same for national averages)

These comparisons are useful for determining need among local populations for our non-profit, but it's difficult to get comparisons this specific or relevant, but we apparently used to. I'm willing to learn PUMS, but after looking at the manual, I want to be sure there isn't a more direct route I'm missing. Thank you for reading - any advice is greatly appreciated.


David

Parents
  • over 4 years ago
    I'm going to give my advice -- for any one who is new (or sort of new) to digging into ACS.
    First piece of advice: Orient yourself by reviewing a list of all the published summary tables in ACS (there's over 1,200 distinct tables).  Here:  www.census.gov/.../table-shells.html  Look for "Table List" link in the middle of the page.
    The data.census.gov portal is *not* good in providing a big picture orientation to ACS.  Instead, I recommend the "Table List." 
    Second thing to know: Most of those published tables are simple tabulations of one ACS question, or crosstabulations of two ACS questions.  There are a few crosstabs that utilize 3 ACS questions. If you're wanting to crosstab four different attributes -- as you say in your email -- sorry, you probably won't find it in the published summary tables.
    So, yes, you will have to resort to building up your own crosstabs from PUMS. There are two places to obtain the PUMS data.
    Option A: Large batch download, from Census's so-called "FTP" site www.census.gov/.../access.2018.html  The batch download quickly gets you every variable.
    Option B: If you don't want every variable, if you want to pick and choose, then instead use IPUMS, here https://usa.ipums.org/usa/
    (I also recommend IPUMS to people who do not have stats or database software; their website has an online tool, allowing the visitor to build desired crosstabs thru the web interface.)
    Final point: ACS is a sample-based survey (~13% of households). There will be statistical inference error for any crosstabbed estimates you assemble.  The error and uncertainty will escalate the thinner you try to slice the data.  You gave the example of wanting to quantify households that are female-led, foreign-born, poor, and with young children. That's a tall order -- be mindful of the statistical inference error. 
    Good luck!
  • over 4 years ago in reply to Todd Graham

    Thank you for the fast response! I may investigate IPUMS for application with our community needs assessments, as I am going to be the lone researcher for this. I really appreciate knowing the soft "three crosstable" limit, though I wish I weren't just guessing at what crosstables are available.

    I don't have separate database or statistics software, but our state happens to have a reference system which interprets ACS data tables, and I use that as often as possible.

    Thanks again for the IPUMS suggestion - learning a lot this week.

  • over 4 years ago in reply to David

    The problem with PUMS data (as distinct from IPUMS) is that the smallest geography available is the PUMA, which is a statistical area of about 100,000 people -- which may not be as local as you have in mind.

    Also, in terms of knowing what you can get from the detailed tables, it's always a work in progress, but we have pretty good coverage of the primary topical areas at https://censusreporter.org/topics/ including lists of tables which link to pages describing the specific columns available. Maybe it would be useful.

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  • over 4 years ago in reply to David

    The problem with PUMS data (as distinct from IPUMS) is that the smallest geography available is the PUMA, which is a statistical area of about 100,000 people -- which may not be as local as you have in mind.

    Also, in terms of knowing what you can get from the detailed tables, it's always a work in progress, but we have pretty good coverage of the primary topical areas at https://censusreporter.org/topics/ including lists of tables which link to pages describing the specific columns available. Maybe it would be useful.

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