Rich raised an good point. The ACS questionnaire is administered year
round whereas the 2000 Census (used in the change map, page 3) was
administered on April 1. Since both surveys ask about mode of
transportation during the previous week, the time-series comparison is
imperfect (year round avg versus early spring). I added yet another
cautionary footnote to the last map but feel free to shoot me a note if
you have more detailed questions.
-Dave
PS: The earliest ACS estimate for the city dates back to 2006 when bike
commuting was estimated at 3.7%, so I think the citywide uptick we're
seeing year round is real but, again, precision is lacking.
On 12/29/2014 1:15 PM, Richard Schifreen wrote:
This is interesting data, but I'm curious how seasonality was factored into the
data analysis. I suspect the response would be significantly different if the
survey was taken in the winter versus the summer. Rich
----- Original Message -----
From: [email protected]
To: [email protected]
Sent: Monday, December 29, 2014 11:49:07 AM
Subject: Bikies Digest, Vol 74, Issue 12
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Today's Topics:
1. Madison bike commuter maps (David Long)
2. Re: Madison bike commuter maps (Harald Kliems)
3. Re: Madison bike commuter maps (Eric Sundquist)
----------------------------------------------------------------------
Message: 1
Date: Mon, 29 Dec 2014 11:13:35 -0600
From: David Long <[email protected]>
To: [email protected].
Subject: [Bikies] Madison bike commuter maps
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
The Census Bureau recently released 5-year American Community Survey
data showing variation in commuting patterns at the census tract and
block group scales. The maps in the link below help to illustrate those
differences:
https://dl.dropboxusercontent.com/u/39132997/Bike_commuters.pdf
The patterns in the first two are not too surprising but help underscore
that bike commuters represent a significant share of workers in the near
east, near west and downtown neighborhoods.I was glad to see the pattern
in the third map (change in bike commuting) indicating an uptick in
areas adjacent to the major off-street bike corridors on the east and
west sides.
Cheers,
Dave
PS: At these smaller geographic scales, there's a lot of sampling error
in the ACS estimates, so please use with caution.
--
David Long
Applied Population Lab
University of Wisconsin
Phone: 608.262.3097
http://www.apl.wisc.edu/
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