1-year estimates at census tract level

No matter who does the estimate for this sort of thing, one effectively allocates the data at a larger geography (here it would be PUMA) to a lower level geography, here it would be tracts. The second thing you would need to do would be to move them ahead a couple of years, since you would, in effect, be using the 5 year file, which centers 3 years out of date. We are working on this for Social Explorer. But we do not have them ready to go at this point for what you need.

Thank you so much all for your help finding data for this exciting research!

Bernie - I called and they said 2016 LODES should be available in 2 months but no guarantees!

Girma - Thank you for this! Unfortunately, I cannot use FCC data because they use county-level data to estimate block-level population. I am looking to see if the change in population of adjacent tracts (or blocks or block groups) affects transit ridership in these places.

Andrew - Since I really need single-year estimates, I've been thinking about deriving them from ACS' 5-year estimates. The problem is that it's a system of equations with n equations and n+4 unknown. Even using the 2010 Census, I wouldn't be able to get those 3 center years. Is that what you are referring to? Am I missing something?

Please let me know if anyone has other ideas this is super helpful!

Thank you so much all for your help finding data for this exciting research!

Bernie - I called and they said 2016 LODES should be available in 2 months but no guarantees!

Girma - Thank you for this! Unfortunately, I cannot use FCC data because they use county-level data to estimate block-level population. I am looking to see if the change in population of adjacent tracts (or blocks or block groups) affects transit ridership in these places.

Andrew - Since I really need single-year estimates, I've been thinking about deriving them from ACS' 5-year estimates. The problem is that it's a system of equations with n equations and n+4 unknown. Even using the 2010 Census, I wouldn't be able to get those 3 center years. Is that what you are referring to? Am I missing something?

Please let me know if anyone has other ideas this is super helpful!

Could you pool ridership across the comparable years and pair that with ACS 5-year data (e.g. ridership from 2012-2016 to match with ACS 2016 5-year)?

Given your study period and scope, there are few things to keep in mind if you do go with ACS 5-year data (whether to derive your own single-year estimates or use the data as-is)...
1 - Census tract boundaries changed in 2010
2 - Data were re-benchmarked to reflect 2010 Census counts
3 - Tracts with a large group quarters population may show variations that have nothing to do with change "on the ground" (the controlling routine for group quarters at the sub-state level can introduce unexpected noise)

Hi Beth,

Thank you for your response. Unfortunately we can't use 5 year estimates because the trends we are measuring are quite subtle.

What do you mean by data were re-benchmarked in 2010?

Can we get rid of the problem altogether by starting our analysis in 2011?

I hate to say it, but if you're looking for very subtle changes at a small geography, it could be tough to use any ACS data. The margins of error are fairly high, and any tricks you might use to estimate higher 1 year estimates to the tract level will likely exacerbate the issue. LEHD might be a your best bet here, as it uses administrative rather than survey data.

The population control totals used for estimates changed dramatically between 2009 and 2010. See: www.census.gov/.../2010_Change_Population_Controls.pdf
In short, variation you see between 2008/2009 and 2010-present may reflect corrections made during the decennial census, not change "on the ground."

And yes, you could avoid this issue (and the change in census tract boundaries) by starting your analysis in 2010.

Bernie - I wouldn't mind a little margins of error because I am using 100,000s of censustract-year combination. Nonetheless, I agree with you that LEHD/LODES will be my best bet for such subtle changes in small geographies. I was hoping to find something that extends beyond 2015, but hopefully 2016 will come out before the end of the analysis.

Beth - Thank you for the tip. I will also use some ACS data for other parts of the analysis and for comparison. I'll just stick to 2010/2011 and beyond.

Everyone - Thank you so much for your help. This forum has been incredibly helpful!