standard deviation for grouped data

[Anonymous]

Hello 

I have a question and appreciate it if you answer.

I have a table in which the data for sales of different products has been stored daily.

to elaborate more:

each day, the number of sold products is different and for some products, it may be 0 sales.

what I want:

I want to calculate the standard deviation. it would be a one constant number. I want to show the std of #number of sold products as a constant line in the line chart over time.

I tried to this dax codes:

Var e= SUMMARIZE('Reports sale','Reports sale'[Date],"sum1",(sum('Reports sale'[productssold])))

VAR f=CALCULATE(STDEVX.P(e,[sum1]),all(e))

return(f)

I appreicate it if you answer my question

[johnt75]

Try

Standard dev all time =
VAR summaryTable =
    CALCULATETABLE (
        ADDCOLUMNS (
            SUMMARIZE ( 'Reports sale', 'Reports sale'[Date] ),
            "@sales", CALCULATE ( SUM ( 'Reports sale'[productssold] ) )
        ),
        REMOVEFILTERS ( 'Reports sale'[Date] )
    )
RETURN
    STDEVX.P ( summaryTable, [@sales] )

[Anonymous]

hi johnt75, 

Thanks for your response .

I tried your solution, But It does not give me the constant number; when I tried to show it on the table, the std value cahnges over time , and when I drill down to day it becomes 0 . 

 

[Anonymous]

from report[date] table .

[johnt75]

Which table is the Month / Day in your table visual coming from ?