-- Kept for reference only, not the recommended version - see
-- "two baseline variants" above for why.
Change Z-Score = 
VAR _CurrentChange = [Period Change]
VAR _ChangesForContext = 
    FILTER (
        ADDCOLUMNS ( ALL ( <<DateTable>>[<<DateColumn>>] ), "@Change", [Period Change] ),
        NOT ISBLANK ( [@Change] )
    )
VAR _MeanChange = AVERAGEX ( _ChangesForContext, [@Change] )
VAR _StdDevChange = STDEVX.S ( _ChangesForContext, [@Change] )
RETURN ZScore ( _CurrentChange, _MeanChange, _StdDevChange )
 
Change Z-Score (LOO) = 
ZScore ( [Period Change], [Mean Period Change Excl Current], [StdDev Period Change Excl Current] )
 
Change Is Z-Score Outlier = 
VAR _Z = [Change Z-Score (LOO)]
RETURN IF ( ISBLANK ( _Z ), BLANK (), ABS ( _Z ) > 3 )
 
Change Is IQR Outlier = 
VAR _CurrentChange = [Period Change]
VAR _ChangesForContext = 
    FILTER (
        ADDCOLUMNS ( ALL ( <<DateTable>>[<<DateColumn>>] ), "@Change", [Period Change] ),
        NOT ISBLANK ( [@Change] )
    )
VAR _Q1 = PERCENTILEX.INC ( _ChangesForContext, [@Change], 0.25 )
VAR _Q3 = PERCENTILEX.INC ( _ChangesForContext, [@Change], 0.75 )
RETURN IsIQROutlier ( _CurrentChange, _Q1, _Q3 )
 
Change Modified Z-Score = 
VAR _CurrentChange = [Period Change]
VAR _ChangesForContext = 
    FILTER (
        ADDCOLUMNS ( ALL ( <<DateTable>>[<<DateColumn>>] ), "@Change", [Period Change] ),
        NOT ISBLANK ( [@Change] )
    )
VAR _Median = MEDIANX ( _ChangesForContext, [@Change] )
VAR _AbsDevTable = ADDCOLUMNS ( _ChangesForContext, "@AbsDev", ABS ( [@Change] - _Median ) )
VAR _MAD = MEDIANX ( _AbsDevTable, [@AbsDev] )
RETURN ModifiedZScore ( _CurrentChange, _Median, _MAD )
 
Change Is Modified Z-Score Outlier = 
VAR _M = [Change Modified Z-Score]
RETURN IF ( ISBLANK ( _M ), BLANK (), ABS ( _M ) > 3.5 )
 
-- Recomputes mean/stddev/N inline for this test, rather than
-- referencing the standalone Mean/StdDev Period Change measures.
Change Is Grubbs Outlier = 
VAR _CurrentChange = [Period Change]
VAR _ChangesForContext = 
    FILTER (
        ADDCOLUMNS ( ALL ( <<DateTable>>[<<DateColumn>>] ), "@Change", [Period Change] ),
        NOT ISBLANK ( [@Change] )
    )
VAR _MeanChange = AVERAGEX ( _ChangesForContext, [@Change] )
VAR _StdDevChange = STDEVX.S ( _ChangesForContext, [@Change] )
VAR _N = COUNTROWS ( _ChangesForContext )
RETURN IsGrubbsOutlier ( _CurrentChange, _MeanChange, _StdDevChange, _N )
 
-- Same pattern: recomputes inline rather than referencing the
-- standalone Mean/StdDev Period Change measures.
Change Is Gaussian Outlier = 
VAR _CurrentChange = [Period Change]
VAR _ChangesForContext = 
    FILTER (
        ADDCOLUMNS ( ALL ( <<DateTable>>[<<DateColumn>>] ), "@Change", [Period Change] ),
        NOT ISBLANK ( [@Change] )
    )
VAR _MeanChange = AVERAGEX ( _ChangesForContext, [@Change] )
VAR _StdDevChange = STDEVX.S ( _ChangesForContext, [@Change] )
RETURN IsGaussianOutlier ( _CurrentChange, _MeanChange, _StdDevChange )