Statistics · Module 2Module material
EDA, Evidence and Misleading Statistics interview questions
28 questions interviewers ask on this module’s topics, from first principles to the follow-ups. Each comes with a model answer.
Exploratory data analysis
- What is exploratory data analysis, and what should come first?●
- What is a unit of analysis, and why does choosing the wrong one matter?●
- A column has missing values and the table has exact duplicate rows. Should you delete them before the analysis?●●
- Why reindex a daily series to the full calendar?●
- What does a zero in a transaction-based daily count tell you?●●
Charts and presentation
- Why should a bar chart's axis start at zero?●
- A dashboard shows two weeks and claims sustained growth. What do you ask for?●●
- How can smoothing or aggregation hide a change?●●
- Why are dual-axis charts risky?●
Denominators and selection
- What is a base rate?●
- A lender reports a low default rate among approved clients. What can it say about all applicants?●●
- What is wrong with filling unobserved outcomes with zero?●●
- How does selection bias affect an ML model trained on approved applicants?●●
Subgroups and Simpson's paradox
- What is Simpson's paradox?●
- Why did the Berkeley aggregate reverse?●●
- What is standardization, and what question does it answer?●●
- Does the Berkeley table show whether admissions were fair?●●
Selective reporting and survivorship
- What is selective reporting?●
- What is the winner's curse, and how large is it here?●●
- What is survivorship, and how do you guard against it?●●
- Why is early stopping a form of selection?●
Claims, prediction and causation
- A metric rose after a feature launch. Can you attribute the rise to the launch?●●
- Why randomize customers rather than invoices?●●
- A randomized simulation gives a difference of 0.0221. What else belongs in the report?●●
- What is the difference between a prediction claim and a causal claim?●
EDA for an ML decision
- Why seal a holdout before EDA for a model?●●
- A table has no missing cells. Is it clean?●●
- What belongs in an EDA report for a later model?●●