Elaine this application presents some interesting and somewhat
perplexing issues when it come to displaying data from the ACS. First,
the numbers for Idaho are correct. For 2010 there were 4,609 Male
bikers. What is not told is that the MOE is +/- 1,021. For Females
there were 3,505 with a MOE of 1,122. So how would one account for the
MOEs with such a display?
I did not do any significance test but I would imagine that the
comparisons of some states to others, as one would be inclined to do
with the map display, might come out as insignificant given the large
MOEs. Maybe I am wrong since the state samples are large but some
indication would have been nice to know. The same issue arises when
looking at an individual state and looking at each of the six years.
Another minor issue that I noticed is when citing ACS as the source. I
would recommend that we all start getting used to saying which ACS
series we are using. I only assumed since they were showing annual data
starting in 2005 that the source was ACS 1-year (ACS1) data as opposed
to either ACS 3-year (ACS3) or ACS 5-year (ACS5) data. As we get more
multi-year estimates it will be more important for us to make sure we
identify which data series.
I did think it would make a interesting trivia question. For 2010 what
state had the second highest mode share of bike commuters? I would
have never guessed Alaska.
PS. I used the profile generator at the Missouri State data center to
obtain the 1010 ACS1 data
(
http://mcdc1.missouri.edu/acsprofiles/acsprofilemenu.html)
.
Elaine.Murakami(a)dot.gov wrote:
http://www.bts.gov/press_releases/2011/dot166_11/html/dot166_11.html
One of the winners uses ACS of bike commuters. When I have time later
today, I am going to check some of the results, because it is showing
Idaho in the darkest color shading for % bike commuters.
Elaine Murakami
FHWA Office of Planning
206-220-4460 (in Seattle)
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Ed Christopher
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