# Articles by dan

### How to eyeball a standard deviation

March 6, 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 ... [Read more...]

### Tips for drawing a normal distribution

February 27, 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 ... [Read more...]

### What’s the deal with wind chill?

January 22, 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 ... [Read more...]

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

August 15, 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 ... [Read more...]

### Random walking

December 11, 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 ... [Read more...]

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

October 25, 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 ... [Read more...]

### How much will that Texas rain be

August 25, 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 ... [Read more...]

### Five kinds of weather you’ll meet in America

August 1, 2017 |

K-MEANS CLUSTERING, A WORKHORSE OF DATA SCIENCE AND MACHINE LEARNING CLICK TO ENLARGE The USA is a large country. How different are people’s experiences of the weather depending on where they live? To look into this question, we downloaded high temperature data for over 1,300 airport weather stations in the ... [Read more...]

### Weighted population density

June 26, 2017 |

DENSITY THE AVERAGE PERSON EXPERIENCES CLICK TO ENLARGE In Alaska, there’s about one person for each square mile of land. You might picture a typical Alaskan not being able to see the next house. But it’s not that way of course. Most of Alaska is uninhabited. People have ... [Read more...]

### Counterintuitive problem: Everyone in a room keeps giving dollars to random others. You’ll never guess what happens next.

June 19, 2017 |

Sorry for the clickbait title. Couldn't resist. The post Counterintuitive problem: Everyone in a room keeps giving dollars to random others. You’ll never guess what happens next. appeared first on Decision Science News. [Read more...]

### Counterintuitive probability problem of the day

May 24, 2017 |

TWO SHOT RUSSIAN ROULETTE WITH 2 BULLETS OR AN EQUAL CHANCE OF 1 or 3 BULLETS With p as the probability of dying on one shot, this figure shows how to get the probability of living through the game. Peter Ayton is giving a talk today at the London Judgement and Decision Making ... [Read more...]

### Another rule of three, this one in statistics

April 14, 2017 |

Here's another rule of three, this one in statistics. The post Another rule of three, this one in statistics appeared first on Decision Science News. [Read more...]

### How many digits into pi do you need to go to find your birthday?

March 17, 2017 |

FIND YOUR BIRTHDAY IN PI, IN THREE DIFFERENT FORMATS It was Pi Day (March 14, like 3/14, like 3.14, get it?) recently and Time Magazine did a fun interactive app in which you can find your birthday inside the digits of pi. However: 1) They only used one format of birthday, in which July 4... [Read more...]

### Turn your tough decisions into simple rules

August 18, 2016 |

If you know R, you could building simple, accurate decision rules today with this sweet new package. The post Turn your tough decisions into simple rules appeared first on Decision Science News. [Read more...]

### Heuristica: An R package for testing models of binary choice

August 2, 2016 |

It just got a lot easier to simulate the performance of simple heuristics. The post Heuristica: An R package for testing models of binary choice appeared first on Decision Science News. [Read more...]

### How many calories should you eat per day?

July 6, 2016 |

How many calories should you eat per day, based on your age, sex, and activity level? Here are the US government's recommendations. The post How many calories should you eat per day? appeared first on Decision Science News. [Read more...]

### R is now the number two statistical computing program in scholarly use

June 20, 2016 |

We were surprised to see that R has passed SAS for scholarly use. We were surprised because we assumed this would have happened years ago. The post R is now the number two statistical computing program in scholarly use appeared first on Decision Science News. [Read more...]

### Can’t compute the standard deviation in your head? Divide the range by four.

June 17, 2016 |

Suppose you divide the range by four instead of taking the standard deviation. How accurate will you be? The post Can’t compute the standard deviation in your head? Divide the range by four. appeared first on Decision Science News. [Read more...]

### What are the most educated counties in the US?

April 15, 2016 |

The 25 US counties with the highest percentage of bachelors and graduate degrees. The post What are the most educated counties in the US? appeared first on Decision Science News. [Read more...]

### The representative reviewers project for the SJDM conference

April 7, 2016 |

We have a plan to make the conference's review committee representative. The post The representative reviewers project for the SJDM conference appeared first on Decision Science News. [Read more...]
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