Return Previous Row Value - 4ish filters needed?

[kressb]

Hello,

I've tried searching the forums as I think this should be an easy one but I'm stuck.

This is the set up:

I assume it has to be a Calculated Column vs Measure due to the need to reference previous rows.

This is the formula I'm trying to use:

PrevDate.Number 1 =
If(Table[StartDate]>Date(2020,07,01),

If(Table[Number1]<>0,
Calculate(

               sum(Table[Number1]),
               filter(Table,Table[StartDate] = PreviousMonth(Table[StartDate])),
               filter(Table,Table[UniqueID2] = Earlier(Table[UniqueID2])),
               filter(Table,Table[UniqueID1] = Earlier(Table[UniqueID1])),
               filter(Table,Table[Title]= Earlier(Table[Title]))
               ),
0),
0)

Where the 0.80, 0.50, 0.40 are in the picture above, PowerBI only returns blanks.

What am I missing?

[Greg_Deckler · Accepted solution]

@kressb See my article on Mean Time Between Failure (MTBF) which uses EARLIER: http://community.powerbi.com/t5/Community-Blog/Mean-Time-Between-Failure-MTBF-and-Power-BI/ba-p/3395....
The basic pattern is:
Column = 
  VAR __Current = [Value]
  VAR __PreviousDate = MAXX(FILTER('Table','Table'[Date] < EARLIER('Table'[Date])),[Date])

  VAR __Previous = MAXX(FILTER('Table',[Date]=__PreviousDate),[Value])
RETURN
  __Current - __Previous

[kressb]

@Greg_Deckler thank you for responding to my posts, your answers are very helpful!