J. Scott Armstrong is a professor at The
Wharton School of the University of Pennsylvania.
He says research on forecasting has been
summarized as 140 scientific principles that must followed to make valid and
useful forecasts (Principles of Forecasting: A Handbook for Researchers and
Practitioners, edited by J. Scott Armstrong, Kluwer Academic Publishers, 2001).
Forecasts made by scientists cannot be
assumed to be 'scientific forecasts' simply because the people making them have science degrees.
Philip E. Tetlock (2005), a psychologist and professor at the University
of Pennsylvania recruited 288 "experts" on political and economic
trends.
Analyzing 82,000 of their forecasts, he
found "experts" barely outperformed non-experts.
I've read other studies where
"experts" underperformed non-experts.
Most important: When predicting the future,
"experts", non-experts, and even village idiots, rarely do better than
flipping a coin!
In 2007, Armstrong and Kesten C. Green of
the Ehrenberg-Bass Institute at the University of South Australia conducted a
“forecasting audit” of the IPCC Fourth Assessment Report (Green and
Armstrong, 2007).
Those forecasting procedures described in
sufficient detail to be evaluated violated 72 forecasting principles.
For example, Green and Armstrong found the
IPCC violated “Principle 1.3: Make sure forecasts are independent of politics.”
Green and Armstrong stated:
“the
IPCC process is directed by non-scientists who have policy objectives and who
believe that anthropogenic (manmade) global warming is real and dangerous.”
They concluded:
"The
forecasts in the (IPCC) Report were not the outcome of scientific procedures.
In
effect, they were the opinions of scientists transformed by mathematics and
obscured by complex writing.
Research
on forecasting has shown that experts’ predictions are not useful in situations
involving uncertainty and complexity.
We
have been unable to identify any scientific forecasts of global warming.
Claims
that the Earth will get warmer have no more credence than saying that it will
get colder. "