DAX Calculations

What is the key difference between a calculated column and a measure in DAX?

• A A calculated column is evaluated in filter context at query time; a measure is stored row by row
• B A calculated column is computed row by row and stored in the model; a measure is computed at query time in filter context ✓
• C Both are identical and interchangeable
• D Measures can only return text; calculated columns can only return numbers

Answer: A calculated column is materialised per row during refresh and consumes storage; a measure is evaluated dynamically at query time based on the surrounding filter context.

What is the primary purpose of the CALCULATE function in DAX?

• A To evaluate an expression in a modified filter context ✓
• B To create a relationship between two tables
• C To concatenate text values
• D To sort a table descending

Answer: CALCULATE evaluates its expression after applying, removing, or overriding filters, making it the central function for changing filter context in DAX.

Which DAX function removes filters from a column or table so a calculation ignores the current filter context (commonly used for a percent-of-total)?

• A RELATED
• B EARLIER
• C ALL ✓
• D FILTER

Answer: ALL removes filters from the specified column(s) or table, returning all rows regardless of context, which is how you compute a stable denominator for percent-of-total measures.

To compute year-to-date sales, which DAX time-intelligence function aggregates directly from the start of the year to the current date?

• A TOTALYTD ✓
• B SAMEPERIODLASTYEAR
• C DATEADD
• D DATESYTD

Answer: TOTALYTD aggregates an expression from the start of the year to the current date in context. DATESYTD returns a date table you would pass into CALCULATE rather than aggregating directly.

In the measure Sales LY = CALCULATE([Total Sales], SAMEPERIODLASTYEAR('Date'[Date])), what does it return?

• A Sales filtered to the latest date only
• B Sales for the next year
• C The running total of sales
• D Total Sales for the equivalent period one year earlier ✓

Answer: SAMEPERIODLASTYEAR shifts the current date context back exactly one year, so the measure returns the prior-year value for the same period.

Which statement about row context is correct?

• A Row context exists when iterating rows, such as in a calculated column or an iterator like SUMX ✓
• B Row context only applies to measures, never to calculated columns
• C Row context is automatically created by a slicer selection
• D Row context always propagates filters across relationships by itself

Answer: Row context refers to the 'current row' during iteration, present in calculated columns and iterator functions (SUMX, AVERAGEX). It does not, by itself, filter related tables.