Tuesday, November 12, 2013

More Rules: Regression towards the Means, Sample Bias, Hot Hand Fallacy

 Regression to the Mean

        There was an experiment to praise and criticize pilots. When the student performed a good landing, the flight instructor praised. Then, the next landing got worse. But when the student performed pretty badly, the instructor criticized. Then, the next flight got better. So the researcher concluded that  criticism works better than praise.          But, in fact, criticism and praise have very little to do with the landing. The main factor is the “regression to the mean”. Suppose you perform a set of experiments. If one sample fall very far from the mean, the next one would be closer to the mean to make up for the large deviation from the mean. So, when the student performed particularly bad, the next landing tended to be better, irrespective of what the instructor might say.

Sample Bias

        When doing a poll, we need to take samples from a group with great diversity so that the sample set can represent the entire population. But that’s not how the media work. A story of patients sick because of bad medication sells better than a story of a patient cured expectedly by the same medication. So, the media tends to show only the bad story. And, again, our feeling is more sensitive to media than numbers. We believe the media, not the fact.

Gambler Fallacy/ Hot Hand Fallacy

        A fair coin would turn heads and tails with equal chance. If you see heads 5 times in a row, the next flip is still has equal chance of turning head and turning tail. But, our feeling doesn’t believe in this. Our feeling tells us that the chance of tail is greater as the coin turns heads more and more.
        The same principle applies to basketball player who taking a good shot for few consecutive time, performing much better than his average. Should we be more worried that he’s not gonna score the next shot because of ‘regression to the mean’.         

SOURCEThe Science of Fear: How the Culture of Fear Manipulates Your Brain 

Book or Audiobooks?

Personally, I prefer audiobooks. It's fun, and I can listen when I'm doing something else. It also makes other activities (e.g., jogging) a lot more fun. For more detail about audiobooks, please read [this post].

There is one more reason that may encourage you to go for the audiobook version. You can get it now for FREE. Audible offers you a free trial for 14 days. Even if you get the book and cancel the subscription right away (so that you don't have to pay), you can keep the book. And, don't worry if you lost the audiobook file. Just log into audible.com. You can keep downloading the over and over again.

   About the summary: It takes time to finish up a book. And, when you do, sometimes, you want to review what you learn from the book. If you do not make  notes as you read, you might have to go through the book once again. This can be time-consuming when you are dealing with a book. But you can still flip through the book and locate what you are looking for.

However, when the material is an audiobook, it is extremely hard to locate a specific part of content. Most likely you will have to listen to the entire audiobook once again.

This book summary will help solve the pain of having to go through the book all over again.

I am leaving out the details of the books. Most books have interesting examples and case studies, not included here. Reading the original book would be much more entertaining and enlightening. If you like the summary, you may want to get the original from the source below.

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