Your AI and Your Data: Don't Let It Make Up the Number
No AI number reaches your report until it passes three questions: what a row is, what it divided by, and what it left out.
You go at your own pace, with your Maestro beside you, 1:1, through the whole course: ask it anything, and it asks you questions too.
15 skills · 5 modules
What you'll be able to do
Each box is a skill. The base is at the bottom, recognizing and explaining, and you work your way up to building something of your own and judging what works and why. Hover over a box to see what it builds on. Click it to see where I teach it and how your Maestro checks it.
- Evaluate
- Synthesize
- Analyze
- Apply
- Understand
Evaluate
Audit a complete AI answer with the three questions
Where I teach it: Ask for it right, then decide · How do you check a full summary an AI wrote?
Builds on:
- Diagnose an average computed at the wrong grain
- Compare groups with rates, not just counts
- Detect rows that were left out of a result
- Detect duplicate rows and measure how much they inflate a total
Your Maestro asks you to judge when it fits and why and saves it as evidence when you do.
Decide how much to check a number based on what is at stake
Where I teach it: Ask for it right, then decide · When can you trust a number from an AI?
Builds on:
- Audit a complete AI answer with the three questions
- Explain why an AI's number needs checking
Your Maestro asks you to judge when it fits and why and saves it as evidence when you do.
Synthesize
Design a question whose answer can be checked
Where I teach it: Ask for it right, then decide · How do you ask an AI for a number you can check?
Builds on:
- Explain why an AI's number needs checking
- Identify the denominator of an average or percentage
- Detect rows that were left out of a result
Your Maestro asks you to build something of your own with it and saves it as evidence when you do.
Analyze
Diagnose an average computed at the wrong grain
Where I teach it: What a row is · How do you calculate the average ticket when one ticket spans several rows?
Builds on:
- Count at the grain the question asks for
Your Maestro asks you to break a problem down with it and saves it as evidence when you do.
Detect rows that were left out of a result
Where I teach it: What it left out · Why doesn't the AI's table add up to your file's total?
Builds on:
- Explain what happens to empty cells in a calculation
- Recompute a number an AI gave you
Your Maestro asks you to break a problem down with it and saves it as evidence when you do.
Apply
Recompute a number an AI gave you
Where I teach it: Before you believe it · How do you recompute an AI's number with pandas?
Builds on:
- Read a short pandas calculation
Your Maestro asks you to use it on a new case and saves it as evidence when you do.
Count at the grain the question asks for
Where I teach it: What a row is · Is counting rows the same as counting sales?
Builds on:
- Identify what a row of a table represents
- Recompute a number an AI gave you
Your Maestro asks you to use it on a new case and saves it as evidence when you do.
Compare groups with rates, not just counts
Where I teach it: What it divided by · Count or rate? How to compare groups of different sizes
Builds on:
- Identify the denominator of an average or percentage
- Recompute a number an AI gave you
Your Maestro asks you to use it on a new case and saves it as evidence when you do.
Detect duplicate rows and measure how much they inflate a total
Where I teach it: What it left out · How do you find duplicate rows that inflate a total?
Builds on:
- Identify what a row of a table represents
- Recompute a number an AI gave you
Your Maestro asks you to use it on a new case and saves it as evidence when you do.
Understand
Explain why an AI's number needs checking
Where I teach it: Before you believe it · How do you know if the number an AI gave you is right?
Builds on:
- Describe how an assistant computes a number from your table
Your Maestro asks you to explain it in your own words and saves it as evidence when you do.
Describe how an assistant computes a number from your table
Where I teach it: Before you believe it · What does an AI do with your file before it gives you a number?
Your Maestro asks you to explain it in your own words and saves it as evidence when you do.
Read a short pandas calculation
Where I teach it: Before you believe it · How do you recompute an AI's number with pandas?
Your Maestro asks you to explain it in your own words and saves it as evidence when you do.
Identify what a row of a table represents
Where I teach it: What a row is · Is counting rows the same as counting sales?
Your Maestro asks you to explain it in your own words and saves it as evidence when you do.
Identify the denominator of an average or percentage
Where I teach it: What it divided by · What number did the AI divide by to get your percentage?
Builds on:
- Identify what a row of a table represents
Your Maestro asks you to explain it in your own words and saves it as evidence when you do.
Explain what happens to empty cells in a calculation
Where I teach it: What it left out · Does an empty cell count as zero in an average?
Your Maestro asks you to explain it in your own words and saves it as evidence when you do.
What we'll cover
Before you believe it
What a row is
What it divided by
What it left out
Ask for it right, then decide
Common questions
- How much does it cost?
- Nothing. You can read every lesson without creating an account. To run the exercises and talk to your Maestro, you sign in with your email and enroll with one tap, no card needed.
- Do I need to know how to code?
- No. The code in this course is short and works like a calculator: every line is explained on the page, and most of the time you only change a word or a number. It runs in your browser, with nothing to install.
- Does it work if I use Copilot, ChatGPT, or Claude?
- Yes. The three checks don't depend on the assistant: they work for any number an AI calculates from a table of yours, whether it lives in Excel, a CSV, or Google Sheets.
- Do I have to upload data from my job?
- No. The whole course uses made-up data from a fictional hardware store. When you want to practice with your own tables, first check what your company allows you to upload to each assistant.
What you get
- 5 modules and 13 pages, open whenever you want them.
Open to everyone: read all of it, and your Maestro, an AI, answers one question per page, on up to five pages a day.
With a free account: your Maestro for the whole course, always on the page you're on, and the exercises run with nothing to install.
Words you'll meet
In the lessons, tap one to see what it means, or ask your Maestro about it.
Who's teaching you
Sergio Sánchez
I'm Sergio, chekos online. I've worked with data for about ten years, mostly at mission-driven organizations: policy research first, then education, and now early childhood services. In 2018 I started tacosdedatos to share what I was learning, and since then it's been a blog, a podcast, courses, guides, and a community. These days I spend a lot of my time building with AI agents and writing about how I organize my work around them. I share what I've learned; you take what's useful and make it yours.
See you in the course
Your AI and Your Data: Don't Let It Make Up the Number