Blog Archives

Another mixed effects model visualization

November 25, 2019
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Another mixed effects model visualization

Last week, I presented an analysis on the longitudinal development of intelligibility in children with cerebral palsy—that is, how well do strangers understand these children’s speech from 2 to 8 years old. My analysis used a Bayesian nonlinear mixed effects Beta regression model. If some models are livestock and some are pets, this model is my dearest pet. I first started developing it...

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ICC Bot comes online

September 17, 2019
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ICC Bot comes online

I am happy to announce the release of ICC Bot, an app for computing interrater reliability scores using the intraclass correlation coefficient (ICC). A screenshot of ICC Bot, an interactive app for computing intraclass correlation coefficients. The ICC statistic appears in repeated measures or multilevel modeling literature as a way to quantify the similarity...

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Anatomy of a logistic growth curve

February 15, 2019
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Anatomy of a logistic growth curve

In this post, I walk through the code I used to make a nice diagram illustrating the parameters in a logistic growth curve. I made this figure for a conference submission. I had a tight word limit (600 words) and a complicated statistical method (Bayesian nonlinear mixed effects beta regression), so I wanted to use a diagram to carry some of the expository...

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sample_n_of(): a useful helper function

May 23, 2018
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sample_n_of(): a useful helper function

Here’s the problem: I have some data with nested time series. Lots of them. It’s like there’s many, many little datasets inside my data. There are too many groups to plot all of the time series at once, so I just want to preview a handful of them. For a working example, suppose we want to visualize the top 50 American female baby names...

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10 PRINT mazes with ggplot2

10 PRINT mazes with ggplot2

There is a celebrated Commodore 64 program that randomly prints outs / and \ characters and fills the screen with neat-looking maze designs. It is just one line of code, but there is a whole book written about it. 10 PRINT CHR$(205.5+RND(1)); : GOTO 10 Screenshots of the 10 PRINT program in action. Images taken from the 10 PRINT book. The basic idea, from my...

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Ridgelines in bayesplot 1.5.0

April 2, 2018
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Ridgelines in bayesplot 1.5.0

At the end of March, Jonah Gabry and I released bayesplot 1.5.0. The major additions to the package were visualizations using ridgelines and a new plot for PIT diagnostics from LOO validation. I don’t know what that LOO PIT thing is yet, so I’ll ta...

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Recode values with character subsetting

January 9, 2018
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Do you ever have to recode many values at once? It’s a frequent chore when preparing data. For example, suppose we had to replace state abbreviations with the full names: abbs

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Using nonstandard evaluation to simulate a register machine

January 5, 2018
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I recently completed all 25 days of Advent of Code 2017, an annual series of recreational programming puzzles. Each day describes a programming puzzle and illustrates a handful of simple examples of the problem. The puzzle then requires the participant to solve a much, much larger form of the problem. For five or so of the puzzles, I used nonstandard evaluation to implement...

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Secret Santa is a graph traversal problem

November 28, 2017
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Last week at Thanksgiving, my family drew names from a hat for our annual game of Secret Santa. Actually, it wasn’t a hat but you know what I mean. (Now that I think about it, I don’t think I’ve ever seen names drawn from a literal hat before!) In our family, the rules of Secret Santa are pretty simple: The players’ names are...

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Simplifying ggplot2 code by doing nothing

October 10, 2017
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Simplifying ggplot2 code by doing nothing

Recently, I joined the development team for bayesplot, an R package by the Stan team for plotting Bayesian models. Because visualizing Bayesian models in ggplot2 is a recurring topic here, it was a natural fit. So from time to time, I’ll post about some programming techniques and new features we develop in the bayesplot package. For this post, I describe one of strategies I have been using to...

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