Hi, I have made a calculation for running sum over a period longer than 1 year like this: 1. Data Set: DATE (in MM/YYYY format); Value 2. + Date2Year=DateFromMDY(1, ( Month('DATE'n) + ( ( Year('DATE'n) - 2014 ) * 12 ) ), 2015) 3. + Value2Year=CumulativePeriod(_Sum_, 'Value'n, 'Date2Year'n, _Inferred_, _Inferred_, 0, _Full_, {Date}) 4. + No.='Date2Year'n. Format display as Day of Month. "No." is needed to replace "Date2Year" in the Table. Same technic I'm using for calculating: day to day difference, week to week difference, cumulative sum by days in week, etc. I hope it's clear and will help. Robert R.
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