Compare strings in previous month

Power BI is easy when you prep your data. I would add a conditional column using Power Query to indicate if the Mgr level is considered to be a staff promotion. Then you can write a simple DAX formula

CALCULATE(COUNTROWS(Table),table[promotion]="Promotion",table[new column]="from staff")

MattAllington Hi. I don't have access to the data source. I can't add new columns. I want to try to solve this using DAX to avoid having to request a change in the database.

Anonymous , Try a measure like

calculate( count(Table[Promotion]) , filter(Table, Table[Promotion] = "Promotion" && Table[ Managerial Level] in { "Staff" ,"Manager"}))

or

calculate( count(Table[Promotion]) , filter(Table, Table[Promotion] = "Promotion" && Table[ Managerial Level] in { "Staff" }))

Hello Anonymous,

Try with this measure:

Count of Promotions from Staff =
COUNTROWS (
    FILTER (
        ADDCOLUMNS (
            'Table',
            "Previous managerial level",
                VAR __id = 'Table'[ID]
                VAR __date = 'Table'[Date]
                RETURN
                    MAXX (
                        TOPN (
                            1,
                            FILTER (
                                ALL ( 'Table' ),
                                'Table'[ID] = __id
                                    && 'Table'[Date] < __date
                            ),
                            'Table'[Date], DESC
                        ),
                        'Table'[Managerial Level]
                    )
        ),
        [Previous managerial level] = "STAFF"
            && 'Table'[Promotion] = "Promotion"
    )
)