Creating Growth Measures with Missing Data

Formula formated easier to read

Growth MTD =
VAR minperiode =
    CALCULATE (
        MIN ( 'Marketing growth'[AS_OF_DATE] ),
        ALLEXCEPT ( 'Marketing growth', 'Marketing growth'[CONTACT_ROLE] )
    )
VAR actualperiod = 'Marketing growth'[AS_OF_DATE]
VAR contactrole = 'Marketing growth'[CONTACT_ROLE]
VAR previousperiod =
    CALCULATE (
        MAX ( 'Marketing growth'[AS_OF_DATE] ),
        ALLEXCEPT ( 'Marketing growth', 'Marketing growth'[CONTACT_ROLE] ),
        'Marketing growth'[AS_OF_DATE] < actualperiod
    )
VAR actualscontact =
    CALCULATE (
        MAX ( 'Marketing growth'[NUM_CONTACTS] ),
        ALLEXCEPT ( 'Marketing growth', 'Marketing growth'[CONTACT_ROLE] ),
        'Marketing growth'[AS_OF_DATE] = actualperiod
    )
VAR previouscontact =
    CALCULATE (
        MAX ( 'Marketing growth'[NUM_CONTACTS] ),
        ALLEXCEPT ( 'Marketing growth', 'Marketing growth'[CONTACT_ROLE] ),
        'Marketing growth'[AS_OF_DATE] = previousperiod
    )
RETURN
    IF (
        actualperiod = minperiode,
        'Marketing growth'[NUM_CONTACTS],
        actualscontact - previouscontact
    )