I have geospacially clipped census blocks into a new geography to estimate the population for the new area (new area/old area * population estimate).
Is there a method to calculate the new margin of error for these new estimates?
Hi!
To calculate margins of error for derrived estimates (such as when you group across geographies) see Chapter 8 of the Handbook
https://www.census.gov/content/dam/Census/library/publications/2018/acs…
I don't think the handbook--by this omission--is intentionally trying to comment on the appropriateness of working with partial geographies. More to the point, the statistical principles guiding how to…
Yes, that is the correct link for Geocorr (all versions).
As for that R package, it seems very out of date (still using Geocorr 2014 with 2010 geographies) and also fairly limited -- it includes only 11…
If the areas are measured without error you can multiply the Est and MoE by scale factor new_clipped_area/old_area. This assumes that the population is distributed uniformly across the large area. You can calculate the area of intersections using the "sf" R package.
To do better than this you need to know the spatial distribution of the population within the large area. For geographies larger than blocks one way to get is to use decennial census block level counts for the blocks that make up the larger area and the "clipped" area. You can then calculate the scale factor as population_in_clipped_area/population_in large area. Geocorr does this for the available types of geographies in their system. You can get "afact" scale factors based on area or population from the most recent decennial census. The decennial census counts are measured without error.
Dave Dorer
David Dorer, this is a brilliant solution, thank you. As you guessed, I don't want to assume even distributions within areas, so this accommodates that concern. I am familiar with "sf" in R. I've never used Geocorr. Is this the correct site: https://mcdc.missouri.edu/applications/geocorr.html? There also appears to be an R package written to leverage it: https://github.com/jjchern/geocorr .
Dear Abe,
The university of Missouri in cooperation the the Census Bureau hosts Geocorr. I just google geocorr missouri
Glenn RIce handles the internals of geocorr and he monitors the website closely. So if you have any questions about geocorr post them here and Glenn will reply usually the same or next day.
Dave
As for that R package, it seems very out of date (still using Geocorr 2014 with 2010 geographies) and also fairly limited -- it includes only 11 crosswalks out of the hundreds possible in the Geocorr app.