-------- Original Message --------
Subject:        Two color ramps for unemployment yielding 4 different messages
Date:   Wed, 15 Aug 2012 19:46:59 +0000
From:   Weessies, Kathleen <[log in to unmask]>
To:     [log in to unmask] <[log in to unmask]>, Dotson, Daniel
<[log in to unmask]>



Several months ago a time-series unemployment map made the rounds and
got a lot of buzz in social media.  Maybe you remember it:
_http://www.latoyaegwuekwe.com/geographyofarecession.html_
At the time I took issue with this map because it depicted a 5%
unemployment rate as a lurid shade of red then ramped up to purple
(designating almost 3 percentage points to show as purple) and then
black.  So at the end of the time series the great majority of the US is
black and purple.  The only yellow (rays of sunshine) were in tiny
pockets of the great plains.  Of course we all know the unemployment
situation is/was very bad, but is 5% unemployment really a statistic
worthy of alarm?  By that standard, we should have been alarmed 80 of
the 119 years from 1890 and 2009:
_http://upload.wikimedia.org/wikipedia/commons/9/9c/US_Unemployment_1890-2009.gif_
I found the same data source (different time frame) mapped using the
same basic color scheme, but giving the red color to 8% unemployment ,
turns purple at 12% and turns black at 14%
_http://www.bls.gov/lau/maps/twmcort.gif_
Way less tweetable.
Another approach uses a single color ramp.  It puts the middle color at
7% and the darkest color at 15% unemployment
_http://mapscroll.blogspot.com/2009/03/unemployment-in-us.html_
The BLS interactive map uses a single color ramp too, but the data
categories are reminiscent of the top example.  The highest category is
for counties with 10%-60% unemployment.  Is that helpful to anyone, to
lump 10% unemployment in with 60% unemployment? Are we to interpret
those areas as basically lost to civilization?
_http://data.bls.gov/map/MapToolServlet?survey=la_
Musing about statistical literacy and the power of maps,
Kathleen Weessies
Geosciences Librarian
Head, Map Library
Coordinator, Collaborative Technology Labs
Michigan State University Main Library
366 W. Circle Drive W308
East Lansing, MI  48824
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Office phone 517-884-0849