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Calculating Mean Time Between Failures with multiple data groups

Gregory Gegner

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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]

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  • 6 months later...

I have resolved the issue.


1. Create a calculated column Rank([MalfunctStartDate],[Equipment]) I named this "RowIdRank"


2. Create another calculated column First([MalfunctStartDate]) OVER (Intersect([Equipment],Next([RowIdRank]))) - [MalfunctStartDate]




Hope this helps someone in the future!

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  • 1 year later...
I am having an issue with this calculation.  The more failures there are the more accurate the results of this equation.  My problem is that lets say a piece of equipment has only two failures within a short amount of time.  This calculation will show that this equipment has the worst MTBF even though it is actually one of the best performing pieces of equipment.
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