Archive for the 'Bad Statistics' category

Metric Abuse - aka Lying with Statistics

I'm behind the curve a bit here, but I've seen and heard a bunch of
people making really sleazy arguments about the current financial stimulus
package working its way through congress, and those arguments are a perfect
example of one of the classic ways of abusing statistics. I keep mentioning metric errors - this is another kind of metric error. The difference between this and some of the other examples that I've shown is that this is deliberately dishonest - that is, instead of accidentally using the wrong metric to get a wrong answer, in this case, we've got someone deliberately taking one metric, and pretending that it's an entirely different metric in order to produce a desired result.

As I said, this case involves the current financial stimulus package that's working its way through congress. I want to put politics aside here: when it comes to things like this financial stimulus, there's plenty of room for disagreement.
Economic crises like the one we're dealing with right now are really uncharted territory - they're very rare, and the ones that we have records of have each had enough unique properties that we don't have a very good collection of evidence
to use to draw solid conclusions about recoveries from them work. This isn't like
physics, where we tend to have tons and tons of data from repeatable experiments; we're looking at a realm where there are a lot of reasonable theories, and there isn't enough evidence to say, conclusively, which (if any) of them is correct. There are multiple good-faith arguments that propose vastly different ways of trying
to dig us out of this disastrous hole that we're currently stuck in.

Of course, it's also possible to argue in bad faith, by
creating phony arguments. And that's the subject of this post: a bad-faith
argument that presents real statistics in misleading ways.

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Selective Data and Global Warming

May 06 2008 Published by under Bad Statistics

One of the most common sleazy tricks used by various sorts of denialists
comes back to statistics - invalid and deceptive sampling methods. In fact,
the very first real post on the original version of this blog was a shredding of
a paper by Mark and David Geier that did this.

Proper statistical analysis relies on a kind of blindness. Many of the things
that you look for, you need to look for in a way that doesn't rely on any a priori
knowledge of the data. If you look at the data, and find what appears to be an
interesting property of it, you have to be very careful to show that it's
a real phenomena - and you do that by performing blind analyses that demonstrate
its reality.

The reason that I bring this up is because one of my fellow SBers,
Tim Lambert, posted something about a particularly sleazy example of this
by Michael Duffy, a global warming denialist over at his blog, Deltoid.

The situation is that there's a Duffy claims
that global warming stopped in 2002. It didn't. But he makes it look like it did by using a deliberately dishonest way of sampling the data.

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Bad Statistical Reasoning about Weather and Climate

Feb 28 2008 Published by under Bad Statistics

Yet another reader sent me a link to a really annoying article at a site called "Daily Tech". The article has been more than adequately debunked by Darksyde at Daily Kos, but it's a very typical example of a general kind of argument made both for and against global warming, which I find extremely annoying.

The basic argument takes one of two forms:

  1. Wow, look how hot it is today! How can anyone possible deny global
    warming?
  2. Wow, look how cold it is today! How can those idiots believe in global
    warming?

These are both examples of confusing weather with climate. That confusion is a typical example of a common statistical error:
using aggregate data to draw conclusions about specific individuals, or using a single individual to draw conclusions about an aggregate. Individual data points and aggregates are very different things, and you can't just arbitrarily go from one to another.

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Washington State and GOP Vote Counting Fraud?

Feb 11 2008 Published by under Bad Statistics

I've been getting a lot of mail from people asking for my take on
the news about the Washington GOP primary. Most have wanted me to
debunk rumours about vote fixing there, the way that I tried to debunk the
rumours about the Democratic votes back in New Hampshire.

Well, sorry to disappoint those of you who were hoping for a nice debunking
of the idea of fraud, but to me, something sure looks fishy.

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Tag-Teaming with Orac: Bad, Bad Breast Cancer Math in JPANDS

Oct 25 2007 Published by under Bad Statistics

My friend, fellow ScienceBlogger, and BlogFather Orac asked me to take a look at a paper that purportedly shows that abortion is a
causative risk factor for breast cancer, which he posted about
this morning
. When the person who motivated me to start what's turned out to be a shockingly
successful blog asks for something, how could I possibly say no? Especially when it's such a great example
of the misuse of mathematics for political purposes?

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