-------- 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 [log in to unmask] <mailto:[log in to unmask]> Office phone 517-884-0849