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Exploratory Data Analysis Questions

Exploratory Data Analysis is the systematic process of investigating and validating a dataset to understand its structure, content, and quality before modelling or reporting. Core activities include examining schema and data types, computing descriptive statistics such as counts, means, medians, standard deviations and quartiles, and measuring class balance and unique value counts. It covers distribution analysis, outlier detection, correlation and relationship exploration, and trend or seasonality checks for time series. Data validation and quality checks include identifying missing values, anomalies, inconsistent encodings, duplicates, and other data integrity issues. Practical techniques span SQL profiling and aggregation queries using GROUP BY, COUNT and DISTINCT; interactive data exploration with pandas and similar libraries; and visualization with histograms, box plots, scatter plots, heatmaps and time series charts to reveal patterns and issues. The process also includes feature summary and basic metric computation, sampling strategies, forming and documenting hypotheses, and recommending cleaning or transformation steps. Good Exploratory Data Analysis produces a clear record of findings, assumptions to validate, and next steps for cleaning, feature engineering, or modelling.

MediumSystem Design
65 practiced
Design a validation checklist and automated tests to run after daily ETL that ensure features and KPIs used in dashboards stay within expected ranges or distributions (for example, mean within 10% of baseline). Include test types, thresholds, storage of historical baselines, and alerting strategies for the BI team.
MediumTechnical
62 practiced
Design an approach to detect anomalies in daily active users (DAU) by country that accounts for holidays and reporting gaps. Describe the statistical technique (moving baseline, seasonal adjustment, control charts), how you choose thresholds, and how you would present anomalies in a BI dashboard template.
HardTechnical
103 practiced
Design a set of statistical tests to determine whether a spike in daily conversions is statistically significant rather than random fluctuation. Discuss assumptions, test selection (Poisson, binomial proportion test, bootstrap), handling seasonality, multiple comparisons, and how to present p-values or confidence intervals to stakeholders.
HardTechnical
56 practiced
You have 10,000 numeric features and building a full correlation heatmap is infeasible. Propose computational and visualization strategies to summarize relationships at scale and surface the most relevant feature pairs for BI analysts. Discuss dimensionality reduction, clustering, feature grouping, and prioritization heuristics.
HardTechnical
76 practiced
For a fraud detection target with 0.1% positives, propose EDA and sampling strategies to understand feature behavior for rare events. Discuss stratified sampling, oversampling positives, downsampling negatives, use of importance sampling, and how to estimate event rates and confidence intervals for rare categories.

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