Getting Standard Deviation of task completion

Summary

Getting Standard Deviation of task completion

Content

Hi all,

I am getting Standard Deviation of task completion in TASKS table. I was intending to use STDDEV function but I have to use a table column as an expression for this function.This means I could not use this function. I have to get standard deviation for each account ID.

I can use below values:

- Average completion days : avg(date_diff(tasks.completed, tasks.created)/86400)

Square root(sum(power(average - date_diff(tasks.completed, tasks.created)/86400, 2)))

I would appreciate if you provide the formula to get Standard Deviation. Thanks.