What do you want to work on?
Six connected sections. Plan and analyse an experiment and learn the theory behind it, measure impact when a clean test is impossible, sharpen the Python and SQL you use every day, and prepare for the coding interview.
A/B Testing Calculator
Plan a test and analyse your results. Picks the right statistical test for your metric, sizes the sample, and gives a plain-English verdict.
- Sample size & duration planner
- Z-test, Welch's t, delta method, SRM check
- Upload Excel / CSV and get a verdict
A/B Testing Theory
Everything behind the calculator, in the order you need it: from what your data looks like to significance, power, choosing the test, running it honestly and five real cases.
- 8 parts, 30 sections: each one answers the question the last one leaves open
- Interactive charts: CLT, power, peeking, CUPED, multiple testing
- Five end-to-end case studies, from problem to decision
Causal Inference
How to measure a real effect when you can't run a clean A/B test. Five practical methods, when to use each, their limits, and runnable Python.
- Difference-in-Differences, RDD, IV, matching, synthetic control
- Business cases, not textbook proofs
- Formulas & copy-paste Python you can run
Python for Analysts
Practical Python for product analytics — language fundamentals, dataset design, pandas, and six real cases with runnable code and charts.
- Fundamentals: loops, functions, core algorithms
- Dataset design: types, tidy format, clean reads
- Six business cases with real charts
SQL for Analysts
Practice databases and fifteen product tasks — from DAU and conversion to churn, cohorts and window functions. Every query verified on PostgreSQL.
- Joins, NULL logic, dates, CTE, window functions
- Four linked databases with a visible schema
- 15 tasks from easy to medium, with real output
Algorithms for Interviews
The coding round of an analyst interview: the logic behind strings, sorting, two pointers and search — and 82 problems from easy to medium.
- A method: from solving by hand to the code, six families of problems
- 62 easy and 20 medium problems, LeetCode variations included
- Step-by-step traces of every key pattern
Built by a product analyst as an open, bilingual learning resource. Everything runs client-side.