Technical practice
How would you use SQL to prepare data from related tables for analysis?
What to coverSuggested answer focus: Explain joins, filters, grouping, and checks for duplicate or missing records. Describe how you would verify that the resulting dataset matches the intended unit of analysis.
How would you clean a dataset containing inconsistent or missing values?
What to coverSuggested answer focus: Discuss inspecting data types, missingness, duplicates, and inconsistent formats before choosing corrections. Explain how you would document changes and check whether cleaning altered important patterns.
How would you use exploratory data analysis to find useful product or business insights?
What to coverSuggested answer focus: Describe summaries and visualizations that reveal distributions, trends, outliers, and relationships. Distinguish a pattern worth investigating from a conclusion the data can already support.
How would you apply statistics and probability to evaluate an apparent change in a product metric?
What to coverSuggested answer focus: Address variability, sample size, possible confounding factors, and uncertainty. Explain what further analysis would help determine whether the change is meaningful for a decision.
How would you preprocess data and engineer features without leaking information into a model?
What to coverSuggested answer focus: Explain how transformations and feature choices depend on the data and prediction task. Describe fitting preprocessing on training data only and checking that features would be available when predictions are made.
How would you select and validate a machine learning model for a business problem?
What to coverSuggested answer focus: Start with the target, an appropriate baseline, and evaluation metrics aligned with the decision. Discuss validation design, overfitting, and trade-offs among predictive performance, efficiency, and interpretability.
How would you build a reliable data pipeline for analytics or model training?
What to coverSuggested answer focus: Describe collection, transformation, validation, and preparation of datasets. Explain checks for consistency and how documented, repeatable steps help identify faulty inputs or transformations.
How would you make Python analysis of a large dataset more efficient?
What to coverSuggested answer focus: Discuss memory use, suitable data structures, algorithmic complexity, and practical Pandas or NumPy operations. Explain how you would measure a bottleneck before changing code and confirm that results remain correct.
A model's performance drops after a data update. How would you troubleshoot it?
What to coverSuggested answer focus: Compare input quality, feature distributions, preprocessing, validation setup, and model outputs with the earlier version. Describe how you would isolate the cause before deciding whether to correct data, code, features, or the model.
How would you present an analysis in a dashboard or report for a product team?
What to coverSuggested answer focus: Choose visualizations that make the decision, key metric, and relevant comparisons clear. Explain assumptions, data limitations, and what action the evidence does or does not support.
Behavioural practice
Tell me about a time you clarified a data question with a cross-functional partner.
What to coverSuggested answer focus: Use a real situation involving differing goals or definitions, describe how you agreed on the question and measure, and state the result. If your example comes from a project or internship, make your own actions clear.
Tell me about a time you found a data-quality issue that affected an analysis.
What to coverSuggested answer focus: Describe the situation, how you detected and investigated the issue, and the action you took. State the result, including any limits on what the corrected data could support.
Tell me about a time you explained a technical finding to a nontechnical audience.
What to coverSuggested answer focus: Give the situation and decision at stake, then explain how you presented the finding and its uncertainty. Describe the audience's response or resulting decision without overstating your impact.
Tell me about a time an analysis or model did not work as expected.
What to coverSuggested answer focus: Set out the original goal, the evidence that something was wrong, and the steps you took to debug or revise your approach. Close with the result and what you learned.
Tell me about a time you learned a new data-science technique for a project.
What to coverSuggested answer focus: Explain the project need, how you assessed and applied the technique, and the result. Distinguish what you verified in practice from what you had only explored.