Median Calculation Fails with Calculation Groups & Field Parameters in Matrix Visual

Hi mbelt 

If dimension is a field parameter, it cannot dynamically reference in a measure. You will need to create a conditoinal measure that switches to different dimensions depending on the selected value in the slicer

MedianPerMeasureX =
VAR DimOrder = SELECTEDVALUE('Dimension'[Dimension Order])

-- Summary table for Dimension1
VAR SummaryTable1 =
    ADDCOLUMNS(
        ALL('ActualDimTable'[Dimension1]),
        "@Value",
        CALCULATE(
            SELECTEDMEASURE(),
            REMOVEFILTERS('ActualDimTable'[Dimension1])
        )
    )

-- Summary table for Dimension2
VAR SummaryTable2 =
    ADDCOLUMNS(
        ALL('ActualDimTable'[Dimension2]),
        "@Value",
        CALCULATE(
            SELECTEDMEASURE(),
            REMOVEFILTERS('ActualDimTable'[Dimension2])
        )
    )

-- Summary table for Dimension3
VAR SummaryTable3 =
    ADDCOLUMNS(
        ALL('ActualDimTable'[Dimension3]),
        "@Value",
        CALCULATE(
            SELECTEDMEASURE(),
            REMOVEFILTERS('ActualDimTable'[Dimension3])
        )
    )

-- Conditional return
RETURN
    SWITCH(
        TRUE(),
        DimOrder = 1,
            MEDIANX(
                FILTER(SummaryTable1, NOT ISBLANK([@Value])),
                [@Value]
            ),
        DimOrder = 2,
            MEDIANX(
                FILTER(SummaryTable2, NOT ISBLANK([@Value])),
                [@Value]
            ),
        DimOrder = 3,
            MEDIANX(
                FILTER(SummaryTable3, NOT ISBLANK([@Value])),
                [@Value]
            )
    )