A shop
customers, products, orders, order_itemsJoins, baskets, revenue by month, customers who never ordered.
Three jobs close enough to be confused and different enough to fail an interview on. QuantPad trains each one with graded exercises on real tables and measures how far you are from the next level.
Each level counts lessons finished, SQL and pandas exercises solved, puzzles and cards mastered. Nothing is self-declared.
Turns business questions into queries, dashboards and decisions.
Builds, validates and ships predictive models.
Designs how data is stored, moved and trusted across the firm.
Revenue per user includes the users who never paid. Leaving them out answers another question. The exercise checks the statistic and the p-value, not the shape of your code.
from scipy.stats import ttest_ind rev = (users.set_index("id")[["variant"]] .join(payments.groupby("user_id")["amount"].sum()) .fillna({"amount": 0})) # non-payers count a, b = (rev.loc[rev.variant == v, "amount"] for v in "AB") t = ttest_ind(a, b, equal_var=False) result = [t.statistic, t.pvalue]
Learn a table once, then query it in SQL, reshape it in pandas, model it with scikit-learn and compute on it in Julia or C++.
customers, products, orders, order_itemsJoins, baskets, revenue by month, customers who never ordered.
instruments, prices, traders, tradesReturns, volatility, drawdown, VWAP, correlation, P&L.
departments, employeesHierarchies, salaries, the classic self-join.
users, events, paymentsFunnels, retention, A/B tests, who pays and why.
Lessons that end in something you have to make work, then a badge.
From a business question to a trustworthy number: SQL, metrics, cohorts, A/B tests and honest charts. No prerequisite.
Statistics, pandas, supervised and unsupervised learning, evaluation and production: the general data scientist’s toolkit, every idea implemented by hand.
Cleaning, causal features, validation that survives contact with reality. The half of the job that job ads list and courses skip.
The research pipeline for machine learning on market data: measure, clean, split, label, size, and judge honestly.
What is inside the models every desk now uses: training, transformers, decoding, retrieval, serving and evaluation, each with graded puzzles.
Turn filings, calls and news into tested signals and clean data: sentiment, event studies, de-duplication and LLM extraction.
No card, no trial. Sign in and solve your first exercise in under a minute.
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