Nice job Mark-- the motion is entertaining to watch. 

I thought I'd share this visualization with all CTPP fans as well:  I built this a while ago, and it'd be good to have you all look closely to keep me honest too! Do my numbers add up to you? I've used county rather than tract data from CTPP 2006-2010. It does not show commuters that stay within the same county as the project was only interested in long-distance commuters across counties. (Note the bubble size adjuster in the lower right corner that makes the map more navigable.)


Josie Kressner, Ph.D.

Transport Foundry
3423 Piedmont Road NE Suite 481
Atlanta, GA 30305

(m) +1.630.426.9076

On Thu, May 26, 2016 at 3:59 PM Jingjing Zang <> wrote:

Hi Mark,


Thanks for the explanation!

I’m looking at Montgomery county as an example, but had trouble duplicate the results.  I’m assuming that the trip distance filter was the cause.  I wonder how you apply the trip distance filter?  Is it defined by distance between centroids of residence and workplace tracts?





From: [] On Behalf Of Mark Evans
Sent: Thursday, May 26, 2016 3:34 PM
Subject: [CTPP] ACS Commute Visualization


Hey - hope this goes through. I'm Mark Evans and I developed the commuter map. Ed Christopher told me about this listserv. I'm happy to answer any questions that you may have.


I think Penelope mentioned it elsewhere, but the data is from the 2006-2010 ACS tract-tract commuter data.


I calculated a CV using the estimate and the MOE. I've seen some warnings about the high level of error in some of the ACS data with recommendations to include only data with CV < 30-40%. Unfortunately, this removes almost all the data, so the default setting I used is 80%. Even at this high level, it excludes a portion of the estimated commuters at the tract level. In addition, anyone who works and lives in the same tract would not be included.


Thanks for taking a look!

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