Li Tan·Last updated April 2026·Bay Area

I write about measurement, experimentation, and the quieter work of turning messy signals into decisions — from ten years inside Silicon Valley tech, now with AI as a new kind of collaborator.

Currently

Working atOpendoor — Senior Data Scientist
Writing aboutAI-native analytics workflows
ReadingThe Book of Why, by Judea Pearl
Side projectsquiet for now

What lives here

Long-form essays on causal inference, experimentation, and marketing measurement — written slowly, edited ruthlessly, cross-referenced with my own practice.

Some pieces include small interactive demos. All are free to read, subscribe via RSS, or reply by email.

The notebook

10 essays

2026

Apr 9
The Hallucinations Hiding in My Pipeline AI writes code that looks right. Sometimes it is. Often it is not. Your job is to catch it. The AI is only as good as you are at reviewing it.
3 min

2025

Jul 25
Beyond A/B Testing: How I Analyze Real Product Impact Without an Experiment When you cannot randomize, causal inference still gets you closer to the truth. Here is my playbook.
2 min
May 20
From Insights to Actions The hardest part of analytics is not finding the insight. It is getting someone to act on it.
2 min
May 20
A Few Thoughts on DMA Tests Geo tests are one of the most powerful tools for measuring marketing lift. They are also easy to get wrong. Some notes from the field.
2 min
May 19
Is AI Ready to Replace Marketing Data Analysts? Every week another headline says yes. I use AI every day. Here is my honest take.
2 min
May 18
Between MTA and LTA The attribution debate never ends. Here is how I think about it.
2 min
May 18
Quick Walkthrough on Anomaly Detection People think anomaly detection is fancy. Most of the time, it is not.
2 min
May 17
A Brief Intro to Building MMM with Agencies How to work with an agency on Marketing Mix Modeling without losing control of the methodology.
2 min
May 17
Experience Reporting to VPs and Above Early in my career I made every mistake possible presenting to execs. Here is what I learned the painful way.
2 min
May 14
Is Marketing an Art or Science? I get asked this at every conference. Here is my honest answer.
2 min

I write about measurement, experimentation, and the quieter work of turning messy signals into decisions — from ten years inside Silicon Valley tech, now with AI as a new kind of collaborator.

Currently

What lives here

The notebook

Ask the notebook.