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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.

MediumTechnical
0 practiced
How would you quantify and visualize pairwise correlation among 50 numeric features to prioritize candidate features for downstream modeling and dashboards? Discuss choice of correlation metric, dimensionality reduction, clustering, and visualization techniques to surface the most relevant relationships.
MediumTechnical
0 practiced
You are reconciling daily order totals between an OLTP orders table and a data-warehouse orders_agg table; totals diverge for multiple dates. Describe an EDA-driven reconciliation workflow to find the root cause, including joins, timestamp alignment, late-arriving events, status filters, and sampling techniques.
MediumTechnical
0 practiced
Write an SQL approach to compute the Gini coefficient for user spend from users_spend(user_id, spend). Explain steps, potential sorting and cumulative sum requirements, and considerations for very large datasets where exact sorting is expensive.
EasyTechnical
0 practiced
Write a single SQL approach or set of SQL queries to compute percent missing and unique counts for the columns in a table orders(order_id PK, customer_id, amount DECIMAL, placed_at TIMESTAMP, coupon_code VARCHAR). Also describe how you would compute the same summaries using pandas for a sampled dataset in memory.
EasyTechnical
0 practiced
In pandas, which methods and sequence of operations would you use to produce a per-column summary that includes dtype, percent missing, unique count, top value and its frequency, mean/median for numeric columns, and example outliers? Describe the function's interface and expected return structure (no need to write full code).

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