From the creator of "A Collection of Data Science Take-home challenges"

The new way to get ready for data science interviews

Job interview prep material and employee training courses that include product case studies, data science take-home challenges, and AI-powered apps.

Gain inside knowledge by reverse-engineering what happens inside top tech companies.

“ This material helped me so much get a data scientist job at Facebook ”

Menghan Xu

Real Data Science


Practice in advance on challenges just like the ones you will get in the interview, resembling what you will actually do at work


Learn how to answer the hardest product, metric, A/B testing on-site questions. Such as: Should we add a given new feature?, Which metric would you choose for this new feature?, etc.


Reusable solution frameworks for SQL/Python/R exercises just like what you will get in the on-site or shared-screen interview

“ I bought the material and as a result I got a job as a Data Scientist at Pinterest! ”

Dorna Bandari

Data Masked Timeline

40 Data Science Product Questions gets released
The two ebooks cross 10K sales combined. Top 50 creator by revenue on Gumroad
The full course in Product Data Science gets released
The Product DS course passes 1M in sales. Receives teachable award
AI - Sold a B2B Chatgpt-powered app to Colgate
Chatgpt for data scientists course gets released
DataScienceGPT app goes live

Products and features

Interview Material
The original

The original DS takehome challenges: 20 take-home challenges with real world data sets. 4 challenges have detailed solutions with reusable step by step code in Python and R (updated as of 2023)
The original 40 DS product questions with answers. This is a subset of just 40 among all the product questions included in the full course. These 40 questions are introductory and more high-level, while the additional ones in the full course are harder and more applied
[New - 2022] 3 sections on coding questions for DS interviews. Learn how to categorize coding questions and apply a reusable framework to each category, removing randomness from the live coding step. Includes SQL, Python, and R solutions to the hardest questions asked at top tech companies.
Full Course in Product Data Science
The best seller

Learn how to develop product sense, create metrics, and design robust A/B tests
Approved as an employee training expense by >200 companies
Includes everything in the interview material package + R/Python solutions for all the challenges (not just 4) + tons of additional DS Product Questions
12 sections with more than 130 lessons and exercises in total. Code in R, Python, and SQL
Real tech company tables, i.e. user table, event table, A/B test tables, etc.
Unlimited 1:1 support from author throughout the course. Can ask any questions you have about the material or anything related to product data science
AI for Data Scientists
The future

Includes access to the DataScienceGPT app
The course is based on the real-world business experience of having built and subsequently sold a Chatgpt-powered app to a Fortune 500 company (Colgate)
Includes Chatgpt foundational knowledge, real-world projects based on reverse-engineering the code of successful AI products, and step-by-step tutorial on how to build production-ready apps
Only requirement is knowledge of Python or R. No prior AI or Web-Development knowledge required
Unlimited 1:1 support from course author
Straightforward approval as an employee training expense
A job board with only high paid and product-oriented data science jobs

I have been creating educational material related to data science since 2015. Firstly focusing on job interviews (A Collection of Data Science Take-Home Challenges, 40 Data Science Product Questions, DS Coding Course) and, more recently, on employee training (Full Course in Product Data Science and AI for Data Scientists).
The main idea behind all the material is to simulate the actual work data scientists do in top tech companies.

In 2023, I built and sold a Chatgpt app to Colgate, I created a practical Chatgpt course to help people build their own app, and built the DataScienceGPT app.

Prior to all this, I worked as a data scientist for several Silicon Valley tech companies, the last one being Airbnb.

“ Giulio is an excellent advisor for preparing for interviews. Very recommended. ”

Donja Darai, Sr. DS at eBay