Etc: Links for 20th December, 2019

  1. The coolest things that David Perell learnt in 2019. He has a paragraph on Twitter, from Bill Gurley, that I wholeheartedly agree with. Tempers run high on Twitter, true, but it is a magnificent learning tool for me.
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    “One of the examples is a famous New York City physician who was renowned for his ability to predict that patients would get typhoid. He predicted the sickness time and again. He would palpate their tounge (feel around their tongue) and predict, weeks before patients had a single symptom, over and over, and became famous, and as one of his colleagues said, he was a more productive carrier of typhoid than even Typhoid Mary because he was giving his patients Typhoid with his hands. In that case, the feedback he was receiving was reinforcing exactly the wrong lesson.”
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  2. Two articles that I got to read as a consequence of subscribing to Joanna Lobo’s Newsletter (if you are interested in writing, either as a hobby or a career, this is a newsletter worth subscribing to). The first is about the perils of comfort food…
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    “Every meal was meticulously pre-portioned and packaged for every individual. We never ate family-style, which was how I grew up eating, and how I learned that portion control is often not within your control: You are not just eating for yourself, and the choice to eat (and how much) often symbolizes love and affection more than physical nourishment. What is considered a “serving” when your chopsticks keep dipping back into shared plates and the diet app you use doesn’t even know what 鱼香茄子 (Chinese eggplant with garlic sauce) is? How can you not overeat when people were heaping dishes onto your plate without you asking? Is it rude to not finish that tofu someone offered you? What is fullness?”
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  3. “A Zomato spokesperson tells Open they are currently in the process of doing away with their food-reviewing levels. The titles have already been removed from the mobile app, the spokesperson says, and they will soon be removed from the website too. According to her, this has nothing to do with complaints about soliciting money, or restaurants and connoisseurs coming together to bump up an establishment’s ratings. “We are just coming up with a newer version, a new engagement tool for users,” the spokesperson says over the phone.”
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    A long read about gaming restaurant reviews.
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  4. Bourbaki’s influence is still alive and well. Now in “his” 80th year of research, in 2016 “he” published the 11th volume of the “Elements of Mathematics”. The Bourbaki group, with its ever-changing cast of members, still holds regular seminars at the University of Paris.
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    A lovely essay from the Madras Courier about Bourbaki, the “guy”.
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  5. Lots of links to work through in this video, but worth your time! Stats nerds only.

Ec101: Links for 19th December, 2019

  1. “Based on the provided support, it is apparent then that it’s advantageous to be as random as possible for generation of ideas, but sticking with a particular response is predictive of creative originality. So next time your friends say that you are “sooo random,” hold your head up high and keep at it. But don’t forget to spot those brilliant ideas among the dis-order, and focus. Such is the recipe for creativity.”
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    On the benefits of being random.
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  2. “Convex functions play an important role in many areas of mathematics. They are especially important in the study of optimization problems where they are distinguished by a number of convenient properties. For instance, a strictly convex function on an open set has no more than one minimum. Even in infinite-dimensional spaces, under suitable additional hypotheses, convex functions continue to satisfy such properties and as a result, they are the most well-understood functionals in the calculus of variations. In probability theory, a convex function applied to the expected value of a random variable is always bounded above by the expected value of the convex function of the random variable.”
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    That is from the Wikipedia article on convexity, and the next sentence after the excerpt leads us to…
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  3. Jensen’s inequality!
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  4. “The point is subtle and widely misunderstood. Here’s a simple example. Suppose that the average return is 10%. If $100 is invested for two periods the average payoff is $100(1.1)^2=$121. But on average that is not what happens. More typically, you get say 0% in the first period and 20% in the second period, i.e. $100(1.0)*(1.2)=$120. Notice that the average return is exactly the same, 10%, but the total payoff is smaller in the second and more realistic case”
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    And Alex Tabbarok explain why Jensen’s Inequality matters
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  5. As does Nassim Nicholas Taleb.