Generating universes within universes with a single seed
See how one call to set.seed() in R creates an entire predetermined universe of pseudorandom numbers
Andrew Heiss's blog
Andrew Heiss's blog
Latest posts
How to automatically convert TikZ images to SVG with Quarto
Make Quarto convert TikZ graphics to SVG files when rendering to non-LaTeX outputs like HTML, Word, and Typst
How to make your data analysis life easier using Positron, Raycast, and Espanso
Links and resources from my time on Posit’s Data Science Lab in January 2026
How to open a folder as a Positron project with macOS Quick Actions
Add a Quick Action workflow so that you can right click on a folder in Finder to open it in Positron.
How to use Positron’s Connections Pane with DuckDB
Positron’s Connections Pane makes it really convenient to work with most types of databases—here’s how to connect to lighting fast DuckDB files.
Use Positron to run R inside a Docker image through SSH
Running R in Docker containers is great for reproducible projects, but writing and running code in the container can be a hassle. Use Positron to SSH into local Docker containers instead!
Open files in external programs with Positron or Visual Studio Code
Positron is great for code, but macOS has better programs specifically for writing with Markdown. Quickly open a Quarto file in an external program with tasks.
How to use a histogram as a legend in {ggplot2}
Land isn’t unemployed—people are. Here’s how to use R, {ggplot2}, {sf}, and {patchwork} to create a histogram legend in a choropleth map to better see the distribution of values.
How to move Crimea from Russia to Ukraine in maps with R
Natural Earth’s de facto on-the-ground policy conflicts with de jure boundaries. Use {sf} and R to relocate parts of country shapes.
Using USAID data to make fancy world maps with Observable Plot
Manipulate geographic data, change projections, get live data from a database, and make interactive plots with Observable JS
Guide to comparing sample and population proportions with CPS data, both classically and Bayesianly
Download CPS demographic data from IPUMS and use R and {brms} to calculate differences between sample and national proportions with Bayesian ROPE-based inference
Apple Music Wrapped with R
Use R to parse Apple Music XML files and create your own Spotify Wrapped-like stats
Guide to generating and rendering computational markdown content programmatically with Quarto
Learn how to use knitr::knit() in inline chunks to correctly render auto-generated R and markdown content in Quarto documents
Fun with Positron
Combine the best of RStudio and Visual Studio Code in Posit’s new Positron IDE
Calculating the proportion of US state borders that are coastlines
Measuring coastlines is hard and causes fractal paradoxes, but we can use R and {sf} to try!
Calculating birthday probabilities with R instead of math
Probability math is hard. Use brute force simulation to find the probability that a household has a cluster of birthdays.
Visualizing {dplyr}’s mutate(), summarize(), group_by(), and ungroup() with animations
Visually explore how {dplyr}’s more complex core functions work together to wrangle data
Demystifying causal inference estimands: ATE, ATT, and ATU
Explore why we care about the ATE, ATT, and ATU and figure out how to calculate them with observational data
DIY API with Make and {plumber}
Use Make and {plumber} to create your own API and show live data in Quarto with R and Observable JS
How to create separate bibliographies in a Quarto document
Use multibib and Quarto to create separate bibliographies for a document and an appendix
Guide to understanding the intuition behind the Dirichlet distribution
Learn about the Dirichlet distribution and explore how it’s just a fancier version of the Beta distribution
Manually generate predicted values for logistic regression with matrix multiplication in R
This is like basic stats stuff, but I can never remember how to do it—here’s how to use matrix multiplication to replicate the results of predict()
The ultimate practical guide to multilevel multinomial conjoint analysis with R
Learn how to use R, {brms}, {marginaleffects}, and {tidybayes} to analyze discrete choice conjoint data with fully specified hierarchical multilevel multinomial models
How to fill maps with density gradients with R, {ggplot2}, and {sf}
Fix overplotted points on maps by creating bins or filled density gradients using R, {ggplot2}, and {sf}
The ultimate practical guide to conjoint analysis with R
Learn how to use R, {brms}, and {marginaleffects} to analyze conjoint data and find causal and descriptive quantities of interest, both frequentistly and Bayesianly
Road trip analysis! How to use and play with Google Location History in R
Learn how to use R to load and clean and play with all the location history data Google keeps about you and look at some neat plots and tables about our 5,000-mile summer road trip along the way
How to make fancy road trip maps with R and OpenStreetMap
Use R to get geocoded location and routing data from OpenStreetMap and explore our family’s impending 5,000 mile road trip around the USA
A guide to Bayesian proportion tests with R and {brms}
Use R, Stan, and {brms} to calculate differences between categorical proportions in a principled Bayesian way
Making Middle Earth maps with R
Explore Tolkien’s Middle Earth with R-based GIS tools, including {ggplot2} and {sf}
How old was Aragorn in regular human years?
Use statistical simulation and a hidden table of Númenórean ages from Tolkien’s unpublished works to convert Aragorn’s Dúnedan years to actual human years
One Simple Trick™ to create inline bibliography entries with Markdown and pandoc
By default, pandoc doesn’t include full bibliographic references inline in documents, but with one tweak to a CSL file, you can create syllabus-like lists of citations with full references
How to migrate from BibDesk to Zotero for pandoc-based writing
Tips, tricks, and rationale for converting from a single big BibTeX file to a Zotero database
How to use natural and base 10 log scales in ggplot2
Use the {scales} R package to automatically adjust and format x- and y-axis scales to use log base 10 and natural log values
Marginal and conditional effects for GLMMs with {marginaleffects}
Use the {marginaleffects} package to calculate tricky and nuanced marginal and conditional effects in generalized linear mixed models
Visualizing the differences between Bayesian posterior predictions, linear predictions, and the expectation of posterior predictions
A guide to different types of Bayesian posterior distributions and the nuances of posterior_predict, posterior_epred, and posterior_linpred
Quick and easy ways to deal with long labels in ggplot2
Explore different manual and automatic ways to rotate, dodge, recode, break up, and otherwise deal with long axis labels with ggplot2
Marginalia: A guide to figuring out what the heck marginal effects, marginal slopes, average marginal effects, marginal effects at the mean, and all these other marginal things are
Define what marginal effects even are, and then explore the subtle differences between average marginal effects, marginal effects at the mean, and marginal effects at representative values with the marginaleffects and emmeans R packages
A guide to modeling outcomes that have lots of zeros with Bayesian hurdle lognormal and hurdle Gaussian regression models
Create, manipulate, understand, analyze, interpret, and plot Bayesian hurdle regression models (and a custom hurdle Gaussian model!) using R, the tidyverse, emmeans, brms, and Stan
How to create a(n almost) fully Bayesian outcome model with inverse probability weights
Use a posterior distribution of inverse probability weights in a Bayesian outcome model to conduct (nearly) fully Bayesian causal inference with R, brms, and Stan
How to use Bayesian propensity scores and inverse probability weights
For mathematical and philosophical reasons, propensity scores and inverse probability weights don’t work in Bayesian inference. But never fear! There’s still a way to do it!
A guide to working with country-year panel data and Bayesian multilevel models
How to use multilevel models with R and brms to work with country-year panel data.
A guide to correctly calculating posterior predictions and average marginal effects with multilievel Bayesian models
How to calculate grand means, conditional group means, and hypothetical group means of posterior predictions from multilevel brms models.
A guide to modeling proportions with Bayesian beta and zero-inflated beta regression models
Everything you ever wanted to know about beta regression! Use R and brms to correctly model proportion data, and learn all about the beta distribution along the way.
Do-calculus adventures! Exploring the three rules of do-calculus in plain language and deriving the backdoor adjustment formula by hand
Use R to explore the three rules of do-calculus in plain language and derive the backdoor adjustment formula by hand
How to automatically convert TikZ images to SVG (with fonts!) from knitr
Make knitr and R Markdown convert TikZ graphics to font-embedded SVG files when knitting to HTML
Exploring Pamela Jakiela’s simple TWFE diagnostics with R
Use R to explore possible biases that come from differential treatment timing in two-way fixed effects (TWFE) regression models
Exploring R² and regression variance with Euler/Venn diagrams
Use Venn diagrams to visualize the proportion of an outcome explained by a regression model
AFC Richmond / Ted Lasso cross stitch pattern
Make your own Ted Lasso AFC Richmond crest cross stitch with a free pattern and an Illustrator template
Hex sticker/logo cross stitch pattern
Make your own data science hex logo cross stitch with a free pattern and an Illustrator template
Bayesian (cross stitch) sampler
Make your own Bayesian cross stitch sampler with a free pattern of Bayes Theorem and the accompanying Illustrator template