Calculating Mean Time Between Failures with multiple data groups
I am trying to calculate the Avg time between failures and average it accross groups. The formula below works for 1 group (System ID) but does not work for 2 or more. I have included the data and a sample DXP. I am looking for suggestions to the forumla or approach.
Thanks for the time and effort.
Avg(DateDiff("day",First([MTBF Service Call Start Date]) OVER (Intersect(All([Axis.X]),[System ID],Previous([MTBF Service Call Start Date]))),[MTBF Service Call Start Date])) AS [MTBF], UniqueCount([Service Call Number]) AS [SR Cnt]