During which phase is data auditing and inventory of data sources typically performed?

• A. Evaluation
• B. Data Understanding
• C. Data Preparation
• D. Modeling

Answer: (B)

Identifying what data exists, where it comes from, and how good it is happens during data understanding. In this phase you audit the data sources, inventory their attributes, note data types, distributions, missing values, and data lineage, and describe the dataset in terms of its relevance to the problem. This grounding work informs what data you can actually use and what must be cleaned or transformed, guiding the subsequent data preparation steps. It’s not about building models or evaluating results, and it’s not solely about cleaning—it's about forming a clear picture of the data landscape before you move on.