The Test Set by Posit

Leilani Battle studies how software shapes what we see and believe. The University of Washington professor and co-director of the UW Interactive Data Lab talks with Michael, Hadley, and Wes about an experiment that manipulated people using nothing but loading speed, and why AI models don't seem to recommend charts the way the community that studies charts actually does. Other highlights: rationality's blind spots and a thorough disc golf origin story.
What's inside:
Loading spinners that quietly change what people find
AI models that don't recommend charts like humans do
The blurry line between databases and human factors
A behavior-change experiment for building fairer models
Rationality's role in producing unethical outcomes
Disc golf origin story
A vegan pancake recipe

Joe Cheng is the CTO of Posit and the creator of Shiny. He joins Michael and Hadley to talk about why he almost walked away from AI work entirely over ethics concerns and what it takes to lead a team that didn't necessarily choose you. Plus, why saying yes to everyone is a worse strategy than it sounds. Bonus: Hadley calls out Joe's people-pleasing in real time.
What's inside:
Joe's 2012 self-doubt spiral that accidentally created Shiny
Why Joe almost quit working on AI entirely
The "loaded guns" problem with releasing AI tools
Hadley's blunt leadership style vs. Joe's people-pleasing
Nobody actually wanted to make Joe CTO?
Joe's take on curiosity, duty, and fear as motivators

Caitlin Colgrove is the CTO of Hex, the data workspace for building and sharing data projects using SQL and Python that somehow counts a Sweetgreen chef as a power user. She joins Michael, Hadley, and Isabel to talk about what AI agents actually get wrong in data work (it's not the hallucinations, it's supreme overconfidence), why data teams aren't going anywhere, and how she thinks about building products for humans and agents at the same time.
What's inside
What Hex's Context Studio does, and why it's a data team's new job
More code is now written in Hex by agents than by humans
"My job is to vouch for the correctness of the answer" — redefining the data team
The vibe-coded CEO PR is coming for your data team (if it hasn’t already)
Soulsborne games as couple's therapy, aka, the Elden Ring co-op report

Alex Hillman built one of America's first co-working spaces, wrote a business book in tweets, and recently handed his inbox to a Claude Code agent — not to draft emails, but to notice when a friendship is going cold. In this episode, Alex, Michael, Wes, and Hadley dig into marketing for people who hate marketing, what 20 years of email reveals about your relationships, and why the hardest part of AI-assisted coding was always before you wrote a single line.
What's inside: 
Marketing is really just listening at scale
Building a 20-year relationship database from your sent folder
"Hot rod vs. plumbing" — the two kinds of software you build now
What early internet and the AI boom have in common
The case for reading 20-year-old engineering books with a coding agent
Karaoke philosophy as a framework for community building

Mike Bostock made D3 when the browser was still a joke. He built bl.ocks when people needed somewhere to share their work. Now he's building Observable — reactive notebooks with an AI that actually looks at what it made. In this episode: the three-GIF bar chart that launched 25 years of viz, why open source needs both intrinsic and extrinsic motivation, and why an agent that can't see its own output is likely to be confidently wrong.
What's Inside
The 1998 visualization library that could only make bar charts
Why D3 hit #3 on GitHub, and what killed the gallery
What spreadsheets got right that notebooks ignored for years
"The agent can lie with text, but not with code"
Why Observable scrapped canvases and went back to notebooks
The penguin dataset that exposes AI
Strength training, tennis mind games, and a resurrected Stanford game