Your data contains 5,000 sales transactions across twelve regions. Which node would reduce your data, showing the average sales amount for each region?

Question

Options

• AAggregate node
• BSelect node
• CFilter node
• DDerive node

• A
  6% (3)
• B
  2% (1)
• C
  2% (1)
• D
  91% (49)

Explanation

There appears to be an error in the provided answer key. The correct answer should be A (Aggregate node), not D.

Why A is correct: An Aggregate node is purpose-built to reduce rows by grouping them - here, collapsing 5,000 transactions into 12 rows (one per region) while computing a summary statistic like average sales amount. This is a classic GROUP BY + AVG operation, which is exactly what Aggregate nodes perform.

Why the distractors are wrong:

• B (Select node): Chooses which columns to keep - it doesn't group rows or compute summaries.
• C (Filter node): Removes rows based on a condition (e.g., "sales > 100") but doesn't summarize or reduce groups.
• D (Derive node): Creates a new calculated column on existing rows (e.g., revenue = price × quantity) - it adds a field but keeps all 5,000 rows intact, so it does not reduce the data.

Memory tip: Think "Aggregate = collapse many into one." Whenever a question mentions grouping + a summary stat (average, sum, count, min, max), the Aggregate node is the answer. The key word in the question is reduce - only Aggregate shrinks the row count.

Note for exam prep: Double-check your answer key. If your course materials define "Derive node" differently (some platforms vary), review your specific tool's documentation - but in standard ETL/analytics tooling (Alteryx, KNIME, Tableau Prep, etc.), this is unambiguously an Aggregate node operation.

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