Stats Made Easy

Practical Tools for Effective Experimentation

Sunday, February 12, 2006

Rambling on about hockey sticks and global warming

Being at Excel Center rink to see the Minnesota Wild clobber the Kings of LA at their game last week in Saint Paul and then watching the USA women hockey team beat up their first two foes, Switzerland and Germany, at the Turin (aka Torino) Olympics got me thinking about the technology of hockey sticks. I have fiddled with small scale hockey sticks for in-class experiments* but I wondered if anyone had posted technical detail on the real thing, so I searched the internet. I was very surprised to get numerous hits on global warming! According to BBC News "The hockey stick was a term coined for a chart of temperature variation over the last 1,000 years, which suggested a recent sharp rise in temperature caused by human activities." But then I came across numerous web entries disputing the "hockey stick" as an artifact of principal component analysis, or PCA, which evidently due to improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not. For one detailed opinion on all this, see Being a native of what we Minnesota residents often call the "State of hockey" and a fan of statistics, I find this all very interesting. I do not care to get snowed under with arguments about global warming, but I have put off plans to buy new hockey skates this year -- it was too warm this year to produce good ice at the local outdoor public rink. However, the record temperatures here in Minnesota did not stop the 27th Annual International Eelpout Festival this weekend at Leech Lake. The sheriff did prohibit fishermen from driving their SUVs out on the ice. Earlier this season a bunch of ice anglers lost their vehicles after parking them too close together. SCUBA divers fished the SUVs out from under the ice. Perhaps if the windows were left open they might have trapped some fish hoping for a joy ride.

*See "Tabletop Hockey Meets Goals for Teaching Experimental Design"


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