Blog Archives

Example 9.23: Demonstrating proportional hazards

March 13, 2012
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Example 9.23: Demonstrating proportional hazards

A colleague recently asked after a slide suitable for explaining proportional hazards. In particular, she was concerned that her audience not focus on the time to event or probability of the event. An initial thought was to display the cumulative haz...

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Example 9.21: The birthday "problem" re-examined

February 23, 2012
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Example 9.21: The birthday "problem" re-examined

The so-called birthday paradox or birthday problem is simply the counter-intutitive discovery that the probability of (at least) two people in a group sharing a birthday goes up surprisingly fast as the group size increases. If the group is only 23 peo...

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RStudio in the cloud, for dummies

February 13, 2012
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RStudio in the cloud, for dummies

You can have your own cloud computing version of R, complete with RStudio. Why should you? It's cool! Plus, there's a lot more power out there than you can easily get on your own hardware. And, it's R in a web page. Run it from your tablet. Run i...

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SAS Macro Simplifies SAS and R integration

January 26, 2012
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SAS Macro Simplifies SAS and R integration

Many of us feel very enthusiastic about R. It's free, it features cutting edge applications, it has a large community of users contributing for mutual benefit, and on and on. There are also many things to like about SAS, including stability, backwards...

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Example 9.19: Demonstrating the central limit theorem

January 11, 2012
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Example 9.19: Demonstrating the central limit theorem

A colleague recently asked "why should the average get closer to the mean when we increase the sample size?" We should interpret this question as asking why the standard error of the mean gets smaller as n increases. The central limit theorem shows t...

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Example 9.18: Constructing the fastest relay team via enumeration

January 5, 2012
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Example 9.18: Constructing the fastest relay team via enumeration

In competitive swimming, the medley relay is a team event in which four different swimmers each swim one of the four strokes: freestyle, breaststroke, backstroke, and butterfly. In general, every swimmer might be able swim any given stroke. How can w...

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Example 9.16: Small multiples

November 29, 2011
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Example 9.16: Small multiples

Small multiples are one of the great ideas of graphics visionary Edward Tufte (e.g., in Envisioning Information). Briefly, the idea is that if many variations on a theme are presented, differences quickly become apparent. Today we offer general guida...

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Example 9.15: Bar chart with error bars ("Dynamite plot")

November 22, 2011
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Example 9.15: Bar chart with error bars ("Dynamite plot")

The "dynamite plot", a bar chart plotting the a mean with a error bar, is one of the most reviled types of image among statisticians. Reasons to dislike them are numerous, and are nicely summarized here. (Edward Tufte also suggests they be avoided.) ...

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Example 9.13: Negative binomial regression with proc mcmc

November 8, 2011
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Example 9.13: Negative binomial regression with proc mcmc

In practice, data that derive from counts rarely seem to be fit well by a Poisson model; one more flexible alternative is a negative binomial model. In this SAS-only entry, we discuss how proc mcmc can be used for estimation. An overview of support f...

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Proc report for simple statistics

October 30, 2011
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Proc report for simple statistics

Ken Beath, of Macquarie University, commented on an earlier entry that the best way to generate summary statistics is using proc report. While the best tools might differ, depending on the purpose, we wanted to share Ken's code demonstrating how to re...

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