Census Bureau plans to stop production of 3-year ACS data

Hi Mark,
I'm sure I'm missing something here -- but won't this be a real loss for users who rely on the most up to date information available for smaller geographic areas?
Thanks for sharing.
All best,
Susan

Susan,
The loss of 3-year ACS data would have major implications for those who need data for small geographic areas. We have often used them here at PRB because they provide a nice compromise between reliability and timeliness.

Thanks for clarifying! Now I understand that you were just quoting the Census Bureau, not agreeing that the project can be discontinued without serious negative impact. I'd be happy to be involved in efforts to have this product restored...

I don't often use the 3-year data, but I just found myself looking forward to a 3-year PUMS data set with all 3 years aligned with the 2010 PUMAs. Our PUMA boundaries changed significantly, making it very hard to work with multiple year data that straddle the 2000 and 2010 PUMAs. Would this change affect the 2014 data releases?

I generally find it difficult to use any ACS products 1,3, or -yr because of the MOEs. That said, over the last five or so years I have gravitated to focusing on the 3-yr products for following trends because they, for my needs, give the very best tradeoff between recency and MOEs.

So for general background work, for me, it would be a total loss to lose the 3-yr as the 1-yrs generally have too much error and the 5-yrs are too out of date.

Obviously the population of the geography you are interested in determines what you can reliably use.

stan drezek

My understand of what I've read is that the 2014, or 2012-14 3 year, release this fall will go ahead as scheduled. The 3 year product stops for vintage 2015. I have used 3 year data a lot, especially for communities between 65K and 200K where the 1 year data have unacceptably high MOEs for most data, and I strongly object to discontinuing them. I am unaware of any efforts to consult with users in this decision, and the reference to 3-year as a "temporary product" goes back more than 10 years to the very beginning of ACS. I would argue that it's now an institutionalized product of the same importance as 1 year and 5 year. In my opinion, it would make more sense to stop issuing 5 year products on an annual basis.

My understanding is that this is at root a budget issue. Nonetheless, I think this is a huge loss and a real problem for medium size communities, in that 20K to 250K range, where the one year data is too unstable year to year to use for policy formulation but a five year timeframe for data is very problematic in different ways for determining public policy. In some cases five year values are not really meaningful (What is a five year average or median rent? Is that really that useful a value?). In most cases 5 year data cover too long a period of social change to give a good sense of what is happening on the ground. (Think about 2005-9 or 2008-12 where the economy underwent a major shift and resulted in a lot of tumult and dislocation.)

I have been using 3 year data since it became available as the best compromise between timeliness and accuracy. I'll have a hard time explaining this to the people I work with and for.

[Updated on 2/3/2015 4:52 PM]

The 5 year ACS file is very useful for those of us who look at the characteristics of U.S. immigrants by national origin in different types of geographic areas. Given the small population size of all immigrant groups except Mexicans, the 5-year file is the only ACS file that has sufficient foreign-born cases for many types of analyses. It would be a big mistake to offer up the 5-year ACS in order to keep the 3-year ACS. If cost constraints are the issue, issuing the 5-year on an alternate year basis would not be a major loss but cutting it completely would force immigration researchers to focus on the total foreign born and assume homogeneity within that population. Our research based on the 5-year ACS shows that there is considerable national origin heterogeneity in settlement and integration processes and that can only becomes clear if one has a sample with a sufficient foreign-born cases to permit national origin disaggregation. I might add that the 5-year ACS (2007-11) has a smaller foreign-born sample than the 2000 PUMS 5% decennial file even though the immigrant population continues to increase annually.

It seems clear to me that since the Census Bureau has been collecting ACS data every year now for 2005 and because 5-year data is the most detailed we don't need 3-year data anymore.

Under no circumstances do I advocate cutting out the 5 year data set. The question is: how often should it be issued? I could make an argument for every 5 years, twice a decade, when each edition would have completely new data. One of them could be years 8, 9, 0, 1, 2; this would match the census. Perhaps others can make an argument for more frequent production.

The 3-year does not provide data for all the counties in my study-area or the small block-group size Traffic Analysis Zones (TAZ) that we use for transportation modeling. The yearly offering of 5-year moving averages provides some understanding of trends and helps when I need data for an "off" year. So I would argue for a contiuation of yearly 5-year data releases.

All that said, the arguments for the timeliness of a 3-year set that are made above are persuasive and I would support the continuation of the product based on the need of those who are using it now. A part of me want to get enough samples collected each year to support a 3-year moving average and the spatial resolution we need here! :)

Though I hate to see datasets discontinued, this is the best candidate for elimination. The 1-year offers the most timely results and the 5-year offers aggregation at the smallest level (Block Group) and ZIP Code Tabulation Area. The 3-year offers none of these benefits.

As a demographer for a mid-sized city (134,000 pop) I use the 3-year estimates since they provide the best compromise between timeliness and accuracy. Large areas may be fine with the 1-year estimates, but for smaller places the margins of error are often too high and the three year product is preferred over the one year.

I find all of them useful, the 1 year, 3 year and 5 year, and so don't want to see any of them discontinued. But what's the process? At this point, it's just something the Census Bureau is proposing, right? Will there be a comment period, are population or statistical groups going to lobby to keep them, can we write to our congress people?

My agency uses 3-year ACS data for low-income designation statistically valid surveys. We determine the median family income for specific areas to use in determining representativeness of the sample size. While we could use 5-year data, our Office of Chief Economist suggests the 3-year statistics are the most reliable for this purpose.