Comments on: IPCC AR4: No skill in scientific forecasting

By: Terry Oldberg

Terry Oldberg — Mon, 21 Dec 2009 08:21:44 +0000

I agree that the “projections” vs “predictions” issue is really important but wish to clarify some of the details. The IPCC’s case for regulation of carbon dioxide emissions is a specious one whose apparent validity rests upon confusion of “projections” with “predictions.” In logic, the two entities have different characters.

A “prediction” is a proposition that states the outcome of a statistical event. A prediction has a property that is called its “truth-value.” The “truth-value” is a variable which takes on the values of “true” and “false.” By virtue of the fact that it has a truth-value, a prediction can be false. That it can be false satisfies the condition called “falsifiability” for the associated model to be “scientific.”

A “projection” is a mathematical function that maps the time to the computed global average temperature. As such, a projection lacks a truth-value. The 3 conclusions follow that: A) a projection cannot be false, B) the associated model is non-falsifiable and, C) this model is not”scientific,” by the definition of “scientific.” A “scientific” model is one that provides “scientia,” the Latin word for “verifiable knowledge.”

By: Terry Oldberg

Terry Oldberg — Mon, 21 Dec 2009 07:23:45 +0000

Dr. Curry is quite right in stating that the IPCC models make no forecasts. That they do not make them has the consequence that the IPCC’s models are not “scientific” under the philosophy of science.

A forecast has a property that is called its “truth-value.” A truth-value is a variable which takes on the values of “true” and “false.” That a forecast can be false has the consequence that the associated model is falsifiable. That it is falsifiable satisfies a condition for the model to be “scientific,” under the philosophy of science.

According to the IPCC, its models make “projections.” A projection lacks a truth-value and it follows that the IPCC models fail to satisfy the falsifiability requirement.

By: Jacket

Jacket — Tue, 13 Oct 2009 00:21:56 +0000

Interesting. Prediction markets work because they accumulate and reward expert’s predictions. How should prediction markets work in general if expert opinion can’t be trusted?

By: PeterS

PeterS — Thu, 19 Jul 2007 18:14:55 +0000

Seer reviewed? (then just find the suckers).

By: MarkW

MarkW — Thu, 19 Jul 2007 16:44:07 +0000

The test of time is now down to a few months?

Milesworthy, you were the one who was making the claim that the peer review process adds a mark of excellence to the paper that has been peer reviewed.

Such a belief cannot be validated by real world experience.

By: Steve Sadlov

Steve Sadlov — Thu, 19 Jul 2007 15:32:59 +0000

Yes-man reviewed. Worthless.

By: Steve Milesworthy

Steve Milesworthy — Thu, 19 Jul 2007 15:26:07 +0000

#233 MarkW
No, the comment is related to whether the conclusions drawn by the IPCC authors can be traced to the peer reviewed literature. It is no secret that just because a paper is peer reviewed does not mean it is correct (ideally it should be correct within the bounds of what is known) or that it will stand the test of time.

By: Sam Urbinto

Sam Urbinto — Thu, 19 Jul 2007 15:11:37 +0000

Re #223 (re 219 and 220 re 210 and 208 re 206) Double post, argghh!

I hate it when that happens.

By: MarkW

MarkW — Thu, 19 Jul 2007 14:56:23 +0000

Wasn’t the Hockey Stick peer reviewed?

By: MarkW

MarkW — Thu, 19 Jul 2007 14:06:45 +0000

I see we’re back to the old, “If it’s peer reviewed it must be good” myth.