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I am trying to build an SPC chart on the median value by week
But I do not know the best approach on how to build my chart
1) As I need to find my median shall I write this in the edit script as follows:
This creates an error in the expression
How would I write the UPPER CONTROL LIMIT based on the fact that a median needs to be calculated by week?
Go to Solution.
To calculate your average value by week dimension (for upper control limit) you could use aggr() function:
Avg(aggr(IF([Patient Admitted?] = 1, [Total Wait])/1440), [WeekDimension]))
It calculates your if() expression for each [WeekDimension] value, then avg() aggregates these values.
For stdev() use the same approach.
Thank you for your help
Much appreciated. This works a treat