Tuesday, January 03, 2006

State of Fear while climate changes, as it always has.

An economist article makes some good points about climate change, and it sounds very even handed as you'd expect from one of the few good news magazines in the world, but one troubling aspect was the chart of temperatures:









It has the typical hockey stick aspect, but I knew I'd seen it before
at numberwatch.co.uk, which is a fantastic site and should be required
reading of anyone that discusses statistics. I saw this same graph
here in numberwatch's discussion of chartmanship,

(go read the whole thing)

Let us take some raw data that you wish to present to the lay public, say a plot
of temperature against time:
Now, it is fairly clear that the graph shows
two flattish periods and two rising periods. Let us also suppose, for the sake
of argument, that in order to satisfy your paymasters you need to emphasise the
importance of the second rise, while diminishing that of the first. There are
three techniques that help. The first is to put in a base line at the most
helpful level, which is at the beginning of the period you wish to emphasise.
The second is to chop off the first plateau, which reinforces the illusion that
the second is a natural level. The third is to make use of colour. By perception
and tradition the hot colour is red and the cold colour is blue. The result is a
form of the same chart, but one which gives a completely different impression to
the non-mathematician:










The chart that the economist is using is slightly disingenuous, since
it places the centerline where it wants to back in the happy times of the
50's and 60's instead of the medieval warm period. why aren't we screaming
about global warming that happened in the 1800's?

Anyway. The economist article mentions the only positive development
in all the political attacks, which is that President Bush has started a
program to get more data from all around the world.

Numberwatch's number of the month article even points to a speech
last november by Micheal Chrighton. Which is a much better response
to global warming then State of Fear, which I thought sucked.




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