You have a Power BI model for sales data. You create a measure to calculate the year-to-date sales. You need to compare the year-to-date sales with the previous year for the same time period. Which…

LASTDATE returns the last date in the current filter context, which is not suitable for comparing periods across years.

TOTALYTD calculates the year-to-date total for the current year but does not provide a mechanism to directly compare it to a previous year's equivalent period without further functions.

The SAMEPERIODLASTYEAR DAX function calculates a set of dates that are one year prior to the dates in the current filter context, preserving the day and month. This precisely enables comparing a current year-to-date period with the equivalent period from the previous year.

PREVIOUSYEAR returns all dates of the prior year, not specifically the same period or duration as the current filter context, making it less precise for a 'same period last year' comparison than SAMEPERIODLASTYEAR.