Boston Consulting Group Data Scientist Interview Questions
Practice the exact questions companies are asking right now.
Identify Causes and Solutions for Fashion Profit Decline
Timed Case: Fashion Retail Profit Decline — Diagnose and Recommend Context You are analyzing a fashion retailer whose profit has declined year-over-ye...
Evaluate Campaign Lift with Predictive Analytics and Validation Strategy
Evaluate Marketing Campaign Lift (Weekly SKU-Level, 3 Years) Context You have 3 years of panel data at weekly SKU (and optionally region/store) granul...
Design and sample for credit default prediction
A bank wants a model to predict 90-day credit card default at account-month level for proactive outreach. Class prevalence in production is about 2% d...
Transform messy transactions with pandas
You are given two CSVs. transactions.csv - Columns: txn_id, user_id, ts_iso (ISO8601 with timezone), amount (decimal USD; refunds negative), merchant_...
Summarize impact and lessons from your resume
Give a concise 90-second overview tailored to this role. Then deep-dive one project where you changed a business decision using data: state the object...
Explain AUC, imbalance, losses, and networks
Imbalanced Classification & Regression: ROC/PR, Losses, and Training Strategies You are evaluating a binary classifier and a regression head in a mach...
Build and evaluate imbalanced binary classifier
Take‑home: Imbalanced Binary Classification with Temporal Split, Calibration, and Operating Point Selection Context You are given an event‑level datas...
Unify 7 tables and impute missing values
Using pandas, write a robust function unify_orders(...) that ingests seven dataframes (or CSVs) with possibly inconsistent column casing/whitespace an...
Compute posterior and predictive coin probabilities
Bayesian coin: posterior, prediction, and stopping-time expectation Context - You have two coins and will use the same coin for all flips: - Fair co...
Query top spenders and 7-day growth
Assume 'today' = 2025-09-01. Write a SQL query to: (1) for each model, compute total revenue in the last 7 days (2025-08-26 to 2025-09-01 inclusive) a...
Manipulate and merge DataFrames correctly
Given three pandas DataFrames: customers customer_id, join_date, tier 101, 2025-01-02, gold 102, 2025-02-10, silver 103, 2025-03-05, gold products mod...
Reduce overfitting under constraints
Reduce Overfitting Under Latency Constraints (Tabular Regression) Context (assumed) - You have a tabular regression model with a large generalization ...
Defend MSE over MAE for car prices
Choosing MSE vs. MAE for Car Price Regression (Unscaled USD Target) You are training a regression model to predict car prices in USD. The target varia...
Achieve 0.95 precision via thresholding
Deploying a High-Precision Classifier on an Imbalanced Dataset You are given a binary classification problem with 50,000 samples and ~5% positives. Th...
Build a leak-free sklearn pipeline
Take-home: Imbalanced Binary Classification Pipeline with scikit-learn You are training a binary classifier on tabular data with the following feature...
Transform and aggregate messy event data
Using pandas (vectorized; no loops), clean, combine, and aggregate the following to produce country/plan day-level metrics for 2025-08-31. DataFrames ...
Explain AUC, activations, ensembles, and imbalance
Machine Learning Metrics and Modeling Choices — Multi-part You are given model scores and binary labels for a small dataset and asked to compute ROC A...
Compute averages and binomial/Poisson probabilities
Streaming Mean and Binomial vs Poisson Approximation Part A — Streaming Mean Update You have an existing dataset of N = 1,000 observations with mean 1...
Differentiate Overfitting and Underfitting in Machine Learning
ML/DL Fundamentals for a Recommendation Engine Context You are preparing for a take-home assessment on ML/DL fundamentals relevant to building a recom...
Visualize and Clean SKU Sales Data for Outliers
sales_data +------------+--------+-----------+----------+------------+---------+ | date | sku_id | unit_sold | revenue | promo_flag | store_id|...