Technical interview guide

Calculated Measures & Aggregations

Writing correct aggregations and calculated measures — where subtle mistakes silently produce wrong numbers.

Read: 45 min
Practice MCQs: 25
Interview QA: 25
Edition: v4
Editorial status: Reviewed
Relevant for: Business Intelligence DeveloperData Analyst

Scope: Current DAX and Microsoft Power BI, Tableau calculations and LOD expressions, and LookML measure guidance reviewed 2026-09-04.

Interview QA

Treat each question like a live interview question: answer out loud first (structure, assumptions, tradeoffs), then open the model answer to spot gaps and rehearse a tighter follow-up.

Curated: 2026-10-05 · Written: 2026-10-05 · Reviewed: 2026-10-03

QA-1

Explain row context and filter context with an example.

QA-2

Choose between a measure, calculated column, and upstream transformation.

QA-3

Design and review a CALCULATE expression.

QA-4

Implement line revenue with an iterator.

QA-5

Build a conversion-rate measure with correct totals.

QA-6

Design an end-of-period balance measure.

QA-7

Define blank, zero, and error semantics for a ratio.

QA-8

Diagnose an iterator measure affected by context transition.

QA-9

Choose between replacing, retaining, and removing filters.

QA-10

Implement percent of total without context or security leakage.

QA-11

Design relationship direction for a measure model.

QA-12

Model order-date and ship-date measures.

QA-13

Design year-over-year and prior-period measures.

QA-14

Diagnose an unexpected measure total.

QA-15

Design and test a distinct-customer measure.

QA-16

Design monetary calculation precision and rounding.

QA-17

Define and test BLANK propagation.

QA-18

What is the mechanical difference between implicit and explicit measures in DAX, and why are explicit measures mandatory for advanced aggregations and external tools?

QA-19

Diagnose and optimize a slow calculated measure.

QA-20

Refactor a complex measure with variables.

QA-21

How do you configure and leverage aggregation tables and DAX measures to optimize query performance in composite models?

QA-22

What is the difference between DIVIDE() and the standard division operator (/) in DAX measures, and why is DIVIDE preferred for aggregations?

QA-23

Manage calculated-measure ownership and versioning.

QA-24

Define operational metrics for a calculation layer.

QA-25