Post by marchesarosa on Jan 6, 2012 10:51:08 GMT 1
Error cascade
Posted on January 5, 2012
by Judith Curry
judithcurry.com/2012/01/05/error-cascade/
So…how do you tell when a research field is in the grip of an error cascade? The most general indicator I know is consilience failures. Eventually, one of the factoids generated by an error cascade is going to collide with a well-established piece of evidence from another research field that is not subject to the same groupthink.
The blog Armed and Dangerous has a provocative post entitled: Error Cascade: A definition and examples. Some excerpts:
In medical jargon, an “error cascade” is something very specific: a series of escalating errors in diagnosis or treatment, each one amplifying the effect of the previous one. This is a well established term in the medical literature: this abstract is quite revealing about the context of use.
There’s a slightly different term, information cascade, which is used to describe the propagation of beliefs and attitudes through crowd psychology. Information cascades occur because humans are social animals and tend to follow the behavior of those around them. When the social incentives are right, humans will substitute the judgment of others for their own.
A useful, related concept is preference falsification, the act of misrepresenting one’s desires or beliefs under perceived social pressures. Preference falsification amplifies informational cascades — humans don’t just substitute the judgment of others for their own, they talk themselves into beliefs most around them don’t actually hold but have become socially convinced they should claim to hold!
I use the term “error cascade” in a meaning halfway between the restricted sense of the medical literature and “information cascade”, and I apply it specifically to a kind of bad science, especially bad science recruited in public-policy debates. Ascientific error cascade happens when researchers substitute the reports or judgment of more senior and famous researchers for their own, and incorrectly conclude that their own work is erroneous or must be trimmed to fit a “consensus” view.
But it doesn’t stop there. What makes the term “cascade” appropriate is that those errors spawn other errors in the research they affect, which in turn spawn further errors. It’s exactly like a cascade from an incorrect medical diagnosis. The whole field surrounding the original error can become clogged with theory that has accreted around the error and is poorly predictive or over-complexified in order to cope with it.
Numerous examples are given, but lets cut straight to the climate change chase:
In extreme cases, entire fields of inquiry can go down a rathole for years because almost everyone has preference-falsified almost everyone else into submission to a “scientific consensus” theory that is (a) widely but privately disbelieved, and (b) doesn’t predict or retrodict observed facts at all well. In the worst case, the field will become pathologized — scientific fraud will spread like dry rot among workers overinvested in the “consensus” view and scrambling to prop it up. Yes, anthropogenic global warming, I’m looking at you!
There an important difference between the AGW rathole and the others, though. Errors in the mass of the electron, or the human chromosome count, or structural analyses of obscure languages, don’t have political consequences (I chose Chomsky, who is definitely politically active, in part to sharpen this point). AGW theory most certainly does have political consequences; in fact, it becomes clearer by the day that the IPCC assessment reports were fraudulently designed to fit the desired political consequences rather than being based on anything so mundane and unhelpful as observed facts.
When a field of science is co-opted for political ends, the stakes for diverging from the “consensus” point of view become much higher. If politicians have staked their prestige and/or hopes for advancement on being the ones to fix a crisis, they don’t like to hear that “Oops! There is no crisis!” — and where that preference leads, grant money follows. When politics co-opts a field that is in the grip of an error cascade, the effect is to tighten that grip to the strangling point...
JC comment: I think the the concept of error cascade is interesting and relevant to climate science. I think this particular article goes over the top in essentially dismissing all of AGW as junk science, but I think his perception is correct in that once you start invoking scientific consensus and deniers, you lay yourselves open to the charge of junk science.
more
Posted on January 5, 2012
by Judith Curry
judithcurry.com/2012/01/05/error-cascade/
So…how do you tell when a research field is in the grip of an error cascade? The most general indicator I know is consilience failures. Eventually, one of the factoids generated by an error cascade is going to collide with a well-established piece of evidence from another research field that is not subject to the same groupthink.
The blog Armed and Dangerous has a provocative post entitled: Error Cascade: A definition and examples. Some excerpts:
In medical jargon, an “error cascade” is something very specific: a series of escalating errors in diagnosis or treatment, each one amplifying the effect of the previous one. This is a well established term in the medical literature: this abstract is quite revealing about the context of use.
There’s a slightly different term, information cascade, which is used to describe the propagation of beliefs and attitudes through crowd psychology. Information cascades occur because humans are social animals and tend to follow the behavior of those around them. When the social incentives are right, humans will substitute the judgment of others for their own.
A useful, related concept is preference falsification, the act of misrepresenting one’s desires or beliefs under perceived social pressures. Preference falsification amplifies informational cascades — humans don’t just substitute the judgment of others for their own, they talk themselves into beliefs most around them don’t actually hold but have become socially convinced they should claim to hold!
I use the term “error cascade” in a meaning halfway between the restricted sense of the medical literature and “information cascade”, and I apply it specifically to a kind of bad science, especially bad science recruited in public-policy debates. Ascientific error cascade happens when researchers substitute the reports or judgment of more senior and famous researchers for their own, and incorrectly conclude that their own work is erroneous or must be trimmed to fit a “consensus” view.
But it doesn’t stop there. What makes the term “cascade” appropriate is that those errors spawn other errors in the research they affect, which in turn spawn further errors. It’s exactly like a cascade from an incorrect medical diagnosis. The whole field surrounding the original error can become clogged with theory that has accreted around the error and is poorly predictive or over-complexified in order to cope with it.
Numerous examples are given, but lets cut straight to the climate change chase:
In extreme cases, entire fields of inquiry can go down a rathole for years because almost everyone has preference-falsified almost everyone else into submission to a “scientific consensus” theory that is (a) widely but privately disbelieved, and (b) doesn’t predict or retrodict observed facts at all well. In the worst case, the field will become pathologized — scientific fraud will spread like dry rot among workers overinvested in the “consensus” view and scrambling to prop it up. Yes, anthropogenic global warming, I’m looking at you!
There an important difference between the AGW rathole and the others, though. Errors in the mass of the electron, or the human chromosome count, or structural analyses of obscure languages, don’t have political consequences (I chose Chomsky, who is definitely politically active, in part to sharpen this point). AGW theory most certainly does have political consequences; in fact, it becomes clearer by the day that the IPCC assessment reports were fraudulently designed to fit the desired political consequences rather than being based on anything so mundane and unhelpful as observed facts.
When a field of science is co-opted for political ends, the stakes for diverging from the “consensus” point of view become much higher. If politicians have staked their prestige and/or hopes for advancement on being the ones to fix a crisis, they don’t like to hear that “Oops! There is no crisis!” — and where that preference leads, grant money follows. When politics co-opts a field that is in the grip of an error cascade, the effect is to tighten that grip to the strangling point...
JC comment: I think the the concept of error cascade is interesting and relevant to climate science. I think this particular article goes over the top in essentially dismissing all of AGW as junk science, but I think his perception is correct in that once you start invoking scientific consensus and deniers, you lay yourselves open to the charge of junk science.
more
