Lies, Damned Lies and Statistics

I’ve always been a fan of Mark Twain and Benjamin Disraeli, and this is one of the first concepts we learned in University level statistics course.

It’s interesting to see how people play with statistics, using them to make claims that those in the know can tell are really deceitful.

Let’s look at an example of someone “playing” with stats.

Anthony Watts, over at WUWT, tries to counter NASA claims about the 2000’s being the hottest decade on record and 2009 being the hottest year by comparing them to the admittedly abnormal 1998, a super-El Nino year in which temperatures spiked.

Here’s NASA:

2009 was tied for the second warmest year in the modern record, a new NASA analysis of global surface temperature shows. The analysis, conducted by the Goddard Institute for Space Studies (GISS) in New York City, also shows that in the Southern Hemisphere, 2009 was the warmest year since modern records began in 1880.

2008 was the coolest year of the decade, due to strong cooling of the tropical Pacific Ocean, 2009 saw a return to near-record global temperatures. The past year was only a fraction of a degree cooler than 2005, the warmest year on record, and tied with a cluster of other years — 1998, 2002, 2003, 2006 and 2007 1998 and 2007 — as the second warmest year since recordkeeping began.

Watts is having none of it.  His post “Sanity Check” really is quite stunning and should probably be called “Check your sanity at the door”.

While the press is hyperventilating over NASA GISS recent announcement of the “Hottest Decade Ever“, it pays to keep in mind what happened the last two years of the past decade.

According to NCDC, 2009 temperatures in the US (53.13F) were the 33rd warmest and very close to the long term mean of 52.86F. Since 1998, according to NCDC’s own figures,  temperatures in the US have been dropping at a rate of more than 10 degrees F per century.

Look at that — temps in the US have been dropping at a rate of more than 10 degrees F per century.

Now, either Watts is rilly rilly ignorant about statistics, or he’s not.

What do you think?

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About Policy Lass

Exploring skeptic tales.

4 Responses to “Lies, Damned Lies and Statistics”

  1. Watts seems to be using US temps as a proxy for world temps. It may not be something I would do, but if temps are not rising in the US, is it really “global warming?”

    • Yes it is. A) the US is not the whole wold. not even close.

      B) 1998 was clearly an outlier, so it should not be used as a baseline.

      C) since 1998 isn’t long enough for the trends to emerge from the noise. AKA any trend will have an error estimate that is MUCH greater than the trend itself. One needs a longer time scales.

      see here:
      http://mind.ofdan.ca/?p=2482
      and
      http://mind.ofdan.ca/?p=2332

      Pay particular attention to figure 3 in the second link, and if you can access AGU papers read the whole paper.

    • Ron, do you really think that global warming means that all regions of the world will warm at the same rate? Does the theory say that? Do you understand how a globally averaged temperature is achieved? Do you understand what is absolutely wrong in what Watts posts?

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