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Archive for 'Encyclopedia'

We can’t tell you why you would want to memorize e to 15 places, but we can tell you how

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MEMORIZE e TO 15 PLACES We recently asked a large group of people the question In the number e, how many places to the right of the decimal does the string ‘1828459045’ first occur? Many people replied “two”, which is wrong, but indicates that many people know that e is equal to 2.71828something Assuming you, […]

How to eyeball a standard deviation

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TEST YOUR ESTIMATION SKILLS Click to enlarge Suppose you are looking at the roughly normally distributed data above and you want to visually estimate the standard deviation. What would you guess? 20? 35? How would you do it? In a past post we talked about tips for drawing a normal distribution. In it, we noted […]

Tips for drawing a normal distribution

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KNOW THY INFLECTION POINT Click to Enlarge We have drawn a lot of sorry-looking normal distributions in our life. It’s a shape that’s hard to get down without a lot of practice. Here’s a few tips that can make it easier. Start by marking out standard deviations on the x axis from -3 to +3 […]

Bayes’ Theorem has been used to argue for the existence of God

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BUT NOT BY BAYES   The most important formula in data science was first used to prove the existence of God by Dan Kopf Richard Price, Bayes’ theorem, and God by Martyn Hooper Who is Richard Price? According to our former Prof Stephen Stigler “Roughly half of Bayes’s famous essay was written by Richard Price, […]

What’s the deal with wind chill?

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WIND SPEEDS UP HEAT LOSS Twenty years ago, a German colleague asked me what the deal was with wind chill. I guess they didn’t have it in Germany. I explained it was an attempt to communicate how it feels when there is a low temperature combined with wind.  But my colleague wanted to know how […]

It’s not the heat, it’s the heat index

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PERCEIVED TEMPERATURE Click to enlarge (We got a request for a Celsius version of this post and since we are a full service website we created one and put it here). So, we were wondering, what’s this heat index we hear about? We went to the Wikipedia article on it. It is an index that […]

The 18 cent piece

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WHAT SET OF COINS MINIMIZES THE AVERAGE NUMBER OF COINS NEEDED TO MAKE CHANGE? We draw your attention to the cleverly-titled article What This Country Needs is an 18 Cent Piece. It’s a piece of recreational mathematics that asks the question “what set of coins minimizes the average number of coins needed to make change”? […]

It’s not the heat, it’s the heat index (Celsius edition)

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PERCEIVED TEMPERATURE (CELSIUS EDITION) Click to enlarge (If you would like to see the Fahrenheit version of this post, please go here.) So, we were wondering, what’s this heat index we hear about? We went to the Wikipedia article on it. It is an index that combines air temperature and relative humidity to convert a […]

What is the average temperature on earth?

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ACROSS ALL TIMES, DAYS, AND PLACES We were up at Yale the other week guest lecturing for Shane Frederick, who always hits us up with trivia questions. Here’s one question he asked us: What’s the average temperature on the earth? That is, what’s the average surface temperature over all places on the earth (inhabited or […]

How large is the great Pacific garbage patch?

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1.6 MILLION SQUARE KILOMETERS OF GARBAGE IN PERSPECTIVE This Nature Scientific Reports article gives an update on the size of the Great Pacific Garbage Patch. It is estimated to be four to 16 times larger than previously estimated: 1.6 million square kilometers. While the article does show the patch along with latitude and longitude lines […]