How to add previous week's value successively each month?

[ninos-shiba]

I have a table that has each month and each week and is calculating an average. I was trying to unsuccessfully add the previous week's number successively for each week each month. For example, the first week in October has 2.79. The second week should be 2.79+1.51=4.3. The third week in October should be 4.3+1.99=6.29, and so on and so on, repeating of course for each month (week 1). How would I be able to add either a calculated column or measure to be able to do that?

[Greg_Deckler · Accepted solution]

@ninos-shiba I would not head down the Previous Value route as it leads to sadness and despair. Previous Value aka "Recursion" - Microsoft Power BI Community. Unless it is Power Query and then it is just difficult. In your case, you could do something like:

Measure =
  VAR __MonthStart = MAX('Table'[Month Start])
  VAR __weekinmonth = MAX('Table'[weekinmonth])
  VAR __Table = FILTER(ALL('Table'),[Month Start] = __MonthStart && [weekinmonth]<=__weekinmonth)
RETURN
  SUMX(__Table,[Evals per Rep])