Calculated Risks: How to Know When Numbers Deceive You

Calculated Risks How to Know When Numbers Deceive You At the beginning of the twentieth century H G Wells predicted that statistical thinking would be as necessary for citizenship in a technological world as the ability to read and write But in the twen

  • Title: Calculated Risks: How to Know When Numbers Deceive You
  • Author: Gerd Gigerenzer
  • ISBN: 9780743254236
  • Page: 480
  • Format: Paperback
  • At the beginning of the twentieth century, H G Wells predicted that statistical thinking would be as necessary for citizenship in a technological world as the ability to read and write But in the twenty first century, we are often overwhelmed by a baffling array of percentages and probabilities as we try to navigate in a world dominated by statistics Cognitive scientisAt the beginning of the twentieth century, H G Wells predicted that statistical thinking would be as necessary for citizenship in a technological world as the ability to read and write But in the twenty first century, we are often overwhelmed by a baffling array of percentages and probabilities as we try to navigate in a world dominated by statistics Cognitive scientist Gerd Gigerenzer says that because we haven t learned statistical thinking, we don t understand risk and uncertainty In order to assess risk everything from the risk of an automobile accident to the certainty or uncertainty of some common medical screening tests we need a basic understanding of statistics.Astonishingly, doctors and lawyers don t understand risk any better than anyone else Gigerenzer reports a study in which doctors were told the results of breast cancer screenings and then were asked to explain the risks of contracting breast cancer to a woman who received a positive result from a screening The actual risk was small because the test gives many false positives But nearly every physician in the study overstated the risk Yet many people will have to make important health decisions based on such information and the interpretation of that information by their doctors.Gigerenzer explains that a major obstacle to our understanding of numbers is that we live with an illusion of certainty Many of us believe that HIV tests, DNA fingerprinting, and the growing number of genetic tests are absolutely certain But even DNA evidence can produce spurious matches We cling to our illusion of certainty because the medical industry, insurance companies, investment advisers, and election campaigns have become purveyors of certainty, marketing it like a commodity.To avoid confusion, says Gigerenzer, we should rely on understandable representations of risk, such as absolute risks For example, it is said that a mammography screening reduces the risk of breast cancer by 25 percent But in absolute risks, that means that out of every 1,000 women who do not participate in screening, 4 will die while out of 1,000 women who do, 3 will die A 25 percent risk reduction sounds much significant than a benefit that 1 out of 1,000 women will reap.This eye opening book explains how we can overcome our ignorance of numbers and better understand the risks we may be taking with our money, our health, and our lives.

    One thought on “Calculated Risks: How to Know When Numbers Deceive You”

    1. I cannot recommend this book enough.For me, as a medical student, the day-to-day applications of this book are endless.Basically it teaches you to fully grasp the concept of uncertainty in situations, and convey it to other people in a way that doesn't distort any of the important stuff.I've passed 4 statistics courses so far, and this book is by far the most useful text on correct use of statistics I have ever seen

    2. This book is a shortcut to statistical numeracy. Gigerenzer goes beyond being merely infomative, and helps the reader understand how to interpret, and what questions to ask to get the information needed to properly quantify risks.

    3. Although this book was pretty dense and took me a while to read, I think Gigerenzer did an excellent job of explaining (often convaluted and complex) statistical reasoning in simple terms so that a common (non-mathematically excitable) person can see the error that so many professionals (doctors, lawyers, and scientists) make every day. This book offered me that unique experience when you have felt something to be true for so many years in your life but never quite knew how to put words to the m [...]

    4. Great book. I was surprised to find that it was from 2002 b/c the information about the questionable benefits of regular mammographies in women < 50 was just recently in the news. The book is largely slanted toward other similar examples in health and medicine; the chapter on DNA evidence and how poorly it's presented in court was eye opening.Conversely, great tips for how to obfuscate and take advantage of the general public's innumeracy when you are presenting data.

    5. Worth a read if you want to start thinking about the data that is quoted at you from various sources. How to think about probability & statistics *easily*, the statistical "illiteracy" of professions that need to know better, how stating the same thing in different ways yields different reactions from peopleExcellent book.

    6. Tirando a impressão que tive sobre descrever demais - por vezes falar o que já havia sido falado, dá lindos insights sobre como lidar com informações numéricas de um modo geral.

    7. L'idea di base era ottima: riuscire a dimostrare anche a chi non ha studiato statistica che le probabilità assegnate ad alcuni eventi non sono affatto quelle che si pensa. Anche gli esempi sono scelti in maniera da interessare: vedere come al processo contro O.J. Simpson l'avvocato difensore è riuscito a girare le carte in tavola e convincere la giuria che la probabilità che il suo cliente fosse un assassino fosse molto più bassa della realtà; oppure calcolare come essere positivi a un test [...]

    8. This is a little dry but I’m like an abacus without any beads and I still got through it okay. Apparently, GPs and surgeons are not as numerate as you would hope, so that makes me feel better (or not, if in their hands). Gigerenzer presents many jaw-dropping stories in a soothing Vulcan manner, mainly to do with health screening (breast cancer in particular), DNA as evidence, HIV (as in people being told they have it when they don’t, and vice versa), and the spin put on statistics by using r [...]

    9. Gerd Gigerenzer möchte uns mit seinem Buch "Das Einmaleins der Skepsis" zwei wichtige Dinge vermitteln: Ersten, dass wir uns ' der Illusion der Gewissheit bewusst werden.' und zweitens, dass es Methoden gibt mit denen man Risiken besser verstehen und sie anderen verständlich mitteilen kann. Mich hat dieses Buch sehr fasziniert und begeistert. Ich mag die Art wie Gerd Gigerenzer erklärt und greifbare Beispiele verwendet. Das wird sicher nicht das letzte seiner Bücher sein das ich gelesen habe [...]

    10. About everyday situations which require people to make decisions based on statistics, and the way those statistics are badly misunderstood and miscommunicated. It covers topics such as HIV testing, mammographies, forensic analysis, and their various applications in the legal system. I'd read about probabilistic and natural frequencies before, but until now, I'd never realised what those claims made about the reliability of DNA fingerprinting matches really implied, and how ambiguous the numbers [...]

    11. This knowledge is timeless, and to focus in on just one area the book covers: presently of serious importance for anyone with the opportunity to obtain services from the modern medical system.The February 2012 issue of Scientific American magazine looked at prostate cancer screening, one of the areas this book also uses to showcase and demonstrate it's techniques. The authors of the SciAm article used precisely the same simple techniques for analyzing the data as are presented in this book, and [...]

    12. It's a mesmerizing statistics book. I was surprised to find myself enjoying reading a book about statistics.A mere murmuring of the word 'statistics' is usually enough to give one a headache. But this book, this book does a magic. The author speaks in a gentle and friendly voice, guiding readers into the land of statistics. He claims that the reason why general public, even highly educated ones, are susceptible to pitfalls is because risks are presented in probability. He goes on to say it's nat [...]

    13. People suck at probabilities. Apparently highly-educated professionals like doctors and lawyers are indisputably awful at math. Thinking in terms of natural frequencies—the raw numbers—is better for most people, including the doctors and lawyers who are indisputably awful at math. This awfulness is thrust upon the general public, and it has lead to wrongful imprisonment, unnecessary surgeries, and suicides. Some examples: Researchers and marketers of diagnostic tests are generally woefully ( [...]

    14. Really fascinating book that has changed how I think about medicine.The premise of this non-fiction is that people, in their quest for certainty (particularly in medicine), are not paying attention to what the data is truly saying- which is that there is not as much certainty in medicine as they believe.While the concepts are valid in many fields, the focus of this book is upon medicine. He puts forward some very compelling information about various medical areas (mammograms, AIDS testing, prost [...]

    15. Although we are living in the era of so-called "big data", most people are still surprisingly incapable of understanding uncertainties in their situations and making decisions out of it. This is particularly problematic when it comes to medical problems, which this book mostly concentrates on; mammography and HIV tests are taken as examples, and the author's demonstration of how misinterpreted these tests are by doctors and the general public came as a great shock to me. The author argues, howev [...]

    16. One of those books that makes you wish you would have paid more attention at school math classes. Unfortunately I have to admit that I'm one of those people who wasn't exactly very good in maths and this books pretty much underlines the seriousness of that. This book is about statistics and how to make sense of them. It suggests that instead of using percentages when talking about probabilities we should be using natural frequencies which are easier for us to understand and remember and also whi [...]

    17. Human minds are not adapted to probability.I used to believe, but the author shook my firm believe in this. as a finance "specialist" i always believed that even the trained mind in probabilities had difficulties with imagining and visualising odds. the authors argument in this book is ground-breaking to me. probabilities, percentages and other normalised forms of representing risk are relatively recent. In contrast, natural frequencies result from natural sampling, the process by which humans a [...]

    18. Gigerenzer is on a crusade to reform the way in which probabilities are reported by the legal and medical professions. He wants to make these numbers more comprehensible since must of us are plagued by "innumeracy," the inability to think in numbers. He illustrates how different versions of probability result in wildly different assessments of risk. His preferred reporting method is "natural frequencies". For example, we’re best able to make a decision about a treatment when we’re told the n [...]

    19. Quick summary: In medicine and the law, clouded understanding of risks and probabilities leads to serious negative consequences. Two examples: If you test positive for HIV, your doctor may inform you that it is absolutely certain that you are infected, while the actual probability of being infected could be as low as 50%. If you belong to the 2% of the population who match the description of a wanted criminal, a prosecutor may argue that this means you are 98% likely to be guilty. In actuality, [...]

    20. There is some good stuff in here, mired, unfortunately in cumbersome explanations and unnecessarily complicated stories/scenarios. I had hoped to add this to the toolbox to accompany Innumeracy (which Gigerenzer references), but there are other, better, books out there on the subject. Even the "fun" chapter was clumsy.More's the pity, because, as I said, some good (obfuscated) stuff in here.

    21. Dare to know! This is the best guide I have found so far to avoid the base rate fallacy also called base rate neglect or base rate bias.It also paradoxically but very enlightening teaches you techniques to apply bayesian thinking by re-stating probability problems using frequencies. This should be required reading for physicians, policy makers and project manager, they have too many critical decisions to make to be deceived by the illusion of certainty

    22. The author argues that when it comes to representing information on risks and uncertainty, it is more straightforward and intuitive to use frequencies rather than probabilities in calculating indicators associated with risks including false positive/negative rate. And he asserts that how to set up categories also influences evaluating risks.

    23. Really enjoyed this book, but some chapters were better than others. Overall I'm really interested in the concepts covered. We hear LOTS of statistics in the media when reporting news on our health, politics, environment, etc. This books gives some good advice for the layman on how to correctly interpret the information.

    24. The author was very didactic. His language was precise and unambiguous, without being filled with unnecessary jargon. Frequently, he reiterated many points from early in the book in later chapters. This guy stands firmly by his claims and backs it up with research. I gave this book 4 stars because the content is original and eye-opening. Other math books reference this book.

    25. Interesting treatment of probability and the general inability of humans to calculate risk with accuracy. I especially liked the chapters on better ways to explain likelihood (in unit terms instead of relative percentage chances, which can be highly misleading and inflammatory).

    26. Excellent book. The author gives some very clear illustrations on how statistics can be used to mislead but more importantly, gives examples of how to present data more clearly as well as how to avoid being mislead. The last few chapters are the weaker part of the book.

    27. 확률과 통계에 관한 시야를 단숨에 확 넓혀준다. 미디어와 기업집단이 이익을 위해 절대적 위험도가 아니라 상대적 위험도를 쓰고, 자연빈도가 아니라 백분위 통계를 쓰면서 통계를 어떻게 왜곡하는지를 알려주고, 계산맹 상태에서 벗어나는 법도 알려준다. 돈에 눈이 멀었거나, 계산맹이거나 아니면 둘 다인 의사에 의해 안젤리나 졸리가 유방절제술을 받은 것이 너무 안타까 [...]

    28. Very good discussion of the lack of statistical understanding present not only in the general public but also among experts. The idea of changing the representation of uncertainty from probabilities to natural frequencies is very useful.

    29. One central idea in this book: it is counter-intuitive for people to reason with probabilities (for example when doing Bayesian inference); re-phrasing problems in terms of natural frequencies often helps.Many experimental results across different domains confirm the point.

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