Blog Archives

Navigate the Bermuda Triangle of Mediation Analysis

July 6, 2010
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Navigate the Bermuda Triangle of Mediation Analysis

MYTHS AND TRUTHS ABOUT AN OFTEN-USED, LITTLE-UNDERSTOOD STATISTICAL PROCEDURE If you go to a consumer research conference, you will hear tales of how experiments have undergone particular statistical rites: the attainment of the elusive crossover interaction, the demonstration of full mediation through Baron and Kenny’s sacred procedure, and so on. DSN has nothing against any

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Maps without map packages

July 1, 2010
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Maps without map packages

LATITUDE + LONGITUDE + OVERPLOTTING FIX = MAPS Decision Science News is always learning stuff from colleague, physicist, mathlete, and all-around computer whiz Jake Hofman. Today, it was a quick and clean way to make nice maps in R without using any map packages: just plot the latitude and longitude of your data points (e.g.

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Baseball, basketball, and (not) getting better as time marches on

June 2, 2010
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Baseball, basketball, and (not) getting better as time marches on

PROS ARE NOT GETTING BETTER AT FREE THROWS Rick Larrick recently told Decision Science News that baseball players have been getting better over the years in a couple ways. First, home runs and strikeouts have increased. The careless or clueless reader might note that this is curious, for from the batter’s perspective home runs are

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Tuesday’s child is full of probability puzzles

May 28, 2010
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Tuesday’s child is full of probability puzzles

COUNTERINTUITIVE PROBLEM, INTUITIVE REPRESENTATION Blog posts about counterintuitive probability problems generate lots of opinions with a high probability. Andrew Gelman and readers have been having a lot of fun with the following probability problem: I have two children. One is a boy born on a Tuesday. What is the probability I have two boys? The

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You won, but how much was luck and how much was skill?

May 4, 2010
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You won, but how much was luck and how much was skill?

In baseball, what are the chances the winner will win again against the same opponent the very next day?

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Tipping heuristics

April 28, 2010
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Tipping heuristics

INCREDIBLY SIMPLE CALCULATIONS MADE SIMPLE Yes, we all know how to calculate 15% or 20% exactly, but it’s fun to use tipping heuristics and even more fun to make crowded graphs of how they compare to each other. (Sorry for the junky chart. Open for suggestions, in the words of Tom Waits.) Here are a

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Get at least 12 observations before making a confidence interval?

April 14, 2010
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Get at least 12 observations before making a confidence interval?

How many observations should you have before constructing a confidence interval?

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Score with scoring rules

July 21, 2009
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Score with scoring rules

INCENTIVES TO STATE PROBABILITIES OF BELIEF TRUTHFULLY We have all been there. You are running an experiment in which you would like participants to tell you what they believe. In particular, you’d like them to tell you what they believe to be the probability that an event will occur. Normally, you would ask them. But

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Inference for R

March 24, 2009
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Inference for R

CREATE AUTOMATICALLY UPDATED R CHARTS AND TABLES INSIDE WORD & EXCEL Decision Science News’ imagination has been recently captured by an innovative product called Inference for R. (R as in the open-source language for statistical computation.) To use it, you simply insert some code into your Microsoft Office documents. The Inference product connects to the

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Your flight is moving …

March 1, 2009
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Your flight is moving …

THE VALUE OF NOT FOLLOWING INSTRUCTIONS As Shane Frederick has noted, if you say “A bat and a ball cost $1.10. The bat costs $1 more than the ball. How much is the ball?”, you will notice that the vast majority of your friends will say “10 cents” instead of the correct “5 cents”, because

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