Measure based on Slicer Selection

Hi EmmaWyeth 

Due to I don't know your data model, so I build a sample to have a test.

Sample Table = 
ADDCOLUMNS (
    CALENDAR ( DATE ( 2019, 12, 01 ), DATE ( 2020, 12, 31 ) ),
    "Year", YEAR ( [Date] ),
    "Month", MONTH ( [Date] ),
    "Day", DAY ( [Date] ),
    "WeekNum", WEEKNUM ( [Date], 2 ),
    "Volumn", INT ( RAND () * 100 )
)

Sample Table:

My Volumn is Random for in order to convenience.

Add two calculated columns YearWeekNum and Rank.

YearWeekNum = 'Sample Table'[Year]*100+'Sample Table'[WeekNum]

Rank = RANKX('Sample Table','Sample Table'[YearWeekNum],,ASC,Dense)

Build a Slicer Table by YearWeekNum.

Slicer = VALUES('Sample Table'[YearWeekNum])

Measure:

Measure = 
VAR _Select =
    SELECTEDVALUE ( Slicer[YearWeekNum] )
VAR _SelRank =
    CALCULATE (
        MAX ( 'Sample Table'[Rank] ),
        FILTER ( 'Sample Table', 'Sample Table'[YearWeekNum] = _Select )
    )
VAR _SUM12 =
    SUMX (
        FILTER (
            ALL ( 'Sample Table' ),
            'Sample Table'[Rank] < _SelRank
                && 'Sample Table'[Rank] >= _SelRank - 12
        ),
        'Sample Table'[Volumn]
    )
VAR _AVG12 =
    DIVIDE ( _SUM12, 12 )
VAR _SUMSEL =
    SUMX ( FILTER ( ALL ( 'Sample Table' ), 'Sample Table'[Rank] = _SelRank ), 'Sample Table'[Volumn] )
RETURN
    IF ( _SUMSEL > _AVG12, "Yes", "No" )

Result:

You can download the pbix file from this link: Measure based on Slicer Selection

Best Regards,

Rico Zhou

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