Publications by dan

How much will that Texas rain be

25.08.2017

PUTTING 35 INCHES OF RAIN IN PERSPECTIVE We are always interested in putting numbers into perspective, so we were interested in this article in which they put the Hurricane Harvey’s rain into perspective. They’re predicting 30-40 inches of rain in a few days in Texas. They asked an expert to put that into perspective and he said: Let’s put...

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How long do you need to flip a coin to see a streak?

25.10.2017

STREAK RESULTS FOR LIKELY (>50%) and HIGHLY LIKELY (>99%) Click to enlarge From research on the hot hand to the observation that people don’t create enough streaks when instructed to create pseudo random data, the decision science community is pretty interested in the perception of streaks. One day we got to wonder, how long would you have to f...

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Random walking

11.12.2017

BAGEL SHOP IDEA I was sitting in a bagel shop on Saturday with my 9 year old daughter. We had brought along hexagonal graph paper and a six sided die. We decided that we would choose a hexagon in the middle of the page and then roll the die to determine a direction: 1 up (North) 2 diagonal to the upper right (Northeast) 3 diagonal to the lower r...

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

15.08.2018

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 combines air temperature and relative humidity to convert a...

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What’s the deal with wind chill?

22.01.2019

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 they get the values in charts like these: If you l...

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Tips for drawing a normal distribution

27.02.2019

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 At x=0, draw a point to be the top of the bell cur...

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How to eyeball a standard deviation

06.03.2019

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 that if you follow a normal curve t...

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