Editorial Reviews. musicmarkup.info Review. In the tradition of Innumeracy by John Allen Paulos, German scientist Gerd Gigerenzer offers his own take on numerical . RISK: How should we make decisions when all relevant alternatives, Gigerenzer & Selten Eds. Bounded rationality: The adaptive toolbox. MIT Press. Calculated Risks: How to Know When Numbers Deceive You Gerd Gigerenzer To ask other readers questions about Calculated Risks, please sign up.
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Request PDF on ResearchGate | On Jan 1, , Gerd Gigerenzer and others published Calculated Risks: How to Know When Numbers Deceive You. Calculated Risks. How to Know When Numbers Deceive You. By Gerd Gigerenzer. Trade Paperback. eBook. LIST PRICE $ Price vary by retailer. musicmarkup.info: Calculated Risks: How to Know When Numbers Deceive You Risk Savvy: How to Make Good Decisions by Gerd Gigerenzer Paperback $ . Only 1 left in Get your Kindle here, or download a FREE Kindle Reading App.
The surprising answer, according to this wonderful new book by psychology professor Gerd Gigerenzer, is, at least for most women, probably not. Deciding whether to have a mammogram or other medical screening the book examines several requires people to calculate the risk that is inherent is taking these tests.? This risk is usually poorly known or communicated and, because of this, people can make the wrong decisions and suffer unnecessarily. What risk, you might ask, is there for an asymptommatic woman in having a mammogram? To answer that, look at what could happen.
The test could also indicate that no cancer is present when it is really there—the test could miss the cancer.? This gives false hope and causes a delay in treatment.
But also scary and far more likely is that the test could indicate that cancer is present when it is not.? Doctors and test advocates seem to be unaware of this uncertainty, they have different goals than do the patients who will receive the tests, and they ignore the costs of false positives. How is the uncertainty of a test calculated??
Here is the standard example, given in every introductory statistics book, that does the job. This example, using numbers from Gigerenzer, might look confusing, but read through it because its complexity is central to understanding the his thesis.
If the base rate probability of breast cancer is 0. To answer the question requires a tool called Bayes Rule.? Gigerenzer has shown here, and in other research, that this tool is unnatural and difficult to use and that people consistently poorly estimate the answer. Can you guess what the answer is? If people instead get the same question with the background information in the form of frequencies instead of probabilities they do much better.?
The same example with frequencies is this: If out of every women 77 have breast cancer, and that 7 of these 77 who test positive actually have the disease, then given that someone tests positive for cancer what is the true probability that this person actually has cancer?
Providing diagnostic information in the form of frequencies benefits both patient and doctor because both will have a better understanding of the true risk. What are the costs of false positives?? For breast cancer, there are several.?
Emotional turmoil is the most obvious: testing positive for a dread disease can be debilitating and the increased stress can influence the health of the patient negatively.? There is also the pain of undergoing unnecessary treatment, such as mastectomies and lumpectomies.?
Obviously, there is also a monetary cost. Mammograms can show a noninvasive cancer called ductal carcinoma in situ, which is predominately nonfatal and needs no treatment, but is initially seen as a guess of cancer.
To better understand the logic of Fast-And-Frugal trees and other heuristics, Gigerenzer and his colleagues use the strategy of mapping its concepts onto those of well-understood optimization theories, such as signal-detection theory. A critic of the work of Daniel Kahneman and Amos Tversky , Gigerenzer argues that heuristics should not lead us to conceive of human thinking as riddled with irrational cognitive biases, but rather to conceive rationality as an adaptive tool that is not identical to the rules of formal logic or the probability calculus.
He and his collaborators have theoretically and experimentally shown that many cognitive fallacies are better understood as adaptive responses to a world of uncertainty—such as the conjunction fallacy , the base rate fallacy , and overconfidence.
The analysis of the adaptive toolbox and its evolution is descriptive research with the goal of specifying the core cognitive capacities such as recognition memory and the heuristics that exploit these such as the recognition heuristic. He has developed an ecological approach to risk communication where the key is the match between cognition and the presentation of the information in the environment.
For instance, lay people as well as professionals often have problems making Bayesian inferences , typically committing what has been called the base-rate fallacy in the cognitive illusions literature. Gigerenzer and Ulrich Hoffrage were the first to develop and test a representation called natural frequencies, which helps people make Bayesian inferences correctly without any outside help.
Later it was shown that with this method, even 4th graders were able to make correct inferences.
Once again, the problem is not simply in the human mind, but in the representation of the information. Gigerenzer has taught risk literacy to some 1, doctors in their CMU and some 50 US federal judges, and natural frequencies has now entered the vocabulary of evidence-based medicine.
In recent years, medical schools around the world have begun to teach tools such as natural frequencies to help young doctors understand test results. Intellectual background[ edit ] Intellectually, Gigerenzer's work is rooted in Herbert Simon 's work on satisficing as opposed to maximizing and on ecological and evolutionary views of cognition, where adaptive function and success is central, as opposed to logical structure and consistency, although the latter can be means towards function.