As we've been wrapping our minds around how to redelineate our block groups for better alignment with our TAZs, our colleague Joe Flood greatly aided this effort by creating a tool to identify nesting relationships from an input table of 2010 census blocks with the block groups and TAZs they belong to. He wrote it in Python [https://github.com/dvrpc/BlockGroupTAZ], but was kind enough to make an Executable (.exe) file [https://drive.google.com/drive/u/1/folders/1sMZxn-9352uUV1Bc3Ys7_PzJ9e-OLn5L] for non-coders to download, run, upload an input table, and get the resulting outputs classifying TAZs and block groups by the following nesting relationships.

With it, we've been able to map out where our geographies least align--the "Many TAZs = Many Block Groups" areas--and concentrate our efforts there before examining other areas. Additionally, our "No Population" TAZs are serving as good candidates for special block groups where we may have little to no population but an employment center we'd like reflected in the CTPP workplace tables and destinations for commute flows. See block group and TAZ maps below for our 9-county region. 

Sample input files are provided on GitHub and Google Drive. Replace our block data with your own--keeping the same column headers--and run the tool in your region. Further info on GitHub site ReadMe file and Google Drive Instructions for Using Executable (GetTAZBGNestings.exe).

Hope this helps you in your PSAPing!

Ben