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Bhanu_VA
Helper II
Helper II

Including 0 values when calculating STDEV

Hi,

Let me walk you through a better example.  I am attempting to determine the most recent 6-Month STDEV for sales by product in order to determine variation.  

 

The Sales Data is made up of daily transactions so it contains a   fact_Sales[TransactionDate] and fact_Sales[units] (i.e. sales), but if there are no sales in a given month, then there will be no data for that month. 

 

So, for example, on July 1st, sales for the past 6 months were the following:

 

Jan 100

Feb 125
Apr 140
May 125

Jun 130

 

March is missing because there were no sales.  So, when I calculate STDEV on the data set, it is calculating it over 5 periods, when in fact there were 6, just one happend to be zero.

 

The code(Measure) I am curretly using is:

 

Measure = CALCULATE(STDEV.P('fact_Sales'[units]),DATESINPERIOD('Calendar'[Date],ENDOFMONTH(fact_Sales[TransactionDate]),-6,MONTH))

Instead of using date parameters in the code, I created a calculated column in the date table that gives each Month a unique ID, makes it easier for me.

 

What I need the formula to do is calculate STDEV across the six month period.  If when pulling the monthly sales numbers, it only comes back with 3 periods, then it needs to assume the other 2 periods with a zero value.

 

Thank you for your help with this!!

1 ACCEPTED SOLUTION

@Bhanu_VA Maybe something like this, PBIX is attached below signature. I'm not getting your stated standard deviation values but I added a debugging measure into the PBIX that should help you determine what is going on. With the debugging measure you can see that it is returning 0's for empty months.

Measure StdDev = 
    VAR __Date = MAX('Table'[Date])
    VAR __BeginDate = EOMONTH(__Date,-6)
    VAR __EndDate = EOMONTH(__Date, -1)
    VAR __Table = FILTER(ALL('Table'),[Date]>=__BeginDate && [Date]<=__EndDate)
    VAR __Count = COUNTROWS(__Table)
    VAR __Missing = 6 - __Count
    VAR __MissingTable = 
        SELECTCOLUMNS(
            ADDCOLUMNS(
                GENERATESERIES(1,__Missing,1),
                "rmv",0
            ),
            "rmv",[rmv],
            "Date",[Value]
        )
    VAR __FinalTable = UNION(__Table, __MissingTable)
    VAR __Result = STDEVX.P(__FinalTable,[rmv])
RETURN
    __Result

 


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15 REPLIES 15
Bhanu_VA
Helper II
Helper II

Hi @amitchandak@Greg_Deckler  ,

If you can provide any help, it would be helpful.

 

Thanks

@Bhanu_VA Maybe something like this, PBIX is attached below signature. I'm not getting your stated standard deviation values but I added a debugging measure into the PBIX that should help you determine what is going on. With the debugging measure you can see that it is returning 0's for empty months.

Measure StdDev = 
    VAR __Date = MAX('Table'[Date])
    VAR __BeginDate = EOMONTH(__Date,-6)
    VAR __EndDate = EOMONTH(__Date, -1)
    VAR __Table = FILTER(ALL('Table'),[Date]>=__BeginDate && [Date]<=__EndDate)
    VAR __Count = COUNTROWS(__Table)
    VAR __Missing = 6 - __Count
    VAR __MissingTable = 
        SELECTCOLUMNS(
            ADDCOLUMNS(
                GENERATESERIES(1,__Missing,1),
                "rmv",0
            ),
            "rmv",[rmv],
            "Date",[Value]
        )
    VAR __FinalTable = UNION(__Table, __MissingTable)
    VAR __Result = STDEVX.P(__FinalTable,[rmv])
RETURN
    __Result

 


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DAX is easy, CALCULATE makes DAX hard...

Thanks a ton @Greg_Deckler ,

Tweaked the query a bit according to my scenario. 

Thanks @Greg_Deckler ,

 Apologies for making things difficult for you @Greg_Deckler . I don't see any option to upload the sample file. There is a bit change in dataset and sorry for that. 

Bhanu_VA_0-1673374083525.png

when I calculated Standard Deviation Manually for the past 21 Months(Dec 2017 selected in the Slicer) I got the Standard Deviation as 0.94.

Note: I think I can't afford to create a calculated table, the table is transactional table it's keep growing.

 

Thanks

@Bhanu_VA I didn't create a calculated table, just a measure. You can share a PBIX file on something like OneDrive or Box and post a link here.


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DAX is easy, CALCULATE makes DAX hard...

Hi @Greg_Deckler ,

 

Here is the sample pbix. Please select sep 2022(in the slicer), so that we will have enough data. https://1drv.ms/u/s!AlFPrnIF0lWCfNoRDLODUZdzBvs?e=ruT6bi

 

Thanks

@Bhanu_VA So the Data table should be this?

Date rmv
Jun-20 3
Sep-20 13
Oct-20 1
Nov-20 5
Dec-20 7
Jan-21 6
Feb-21 3
Mar-21 4
Apr-21 7
May-21 1
Jun-21 4
Jul-21 3
Aug-21 1
Sep-21 2
Oct-21 1
Nov-21 1
Dec-21 4
Jan-22 7

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DAX is easy, CALCULATE makes DAX hard...

Hi @Greg_Deckler .

The below link(has pbix) has perfect my kind of scenario. https://1drv.ms/u/s!AlFPrnIF0lWCfNoRDLODUZdzBvs?e=ruT6bi

 

Thanks

Hi @Greg_Deckler ,

 

Any luck with the pbix file I had shared. Tried many ways, nothing worked.

 

Thanks

Hi @Greg_Deckler ,

 

Unfortunately, I can't share my work ondrive link over here, If possible could you please use with the above pasted data.

sorry for the trouble.

 

Thanks

@Bhanu_VA The problem with what you shared is I don't see any data to take a standard deviation of. What am I missing?


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DAX is easy, CALCULATE makes DAX hard...
Bhanu_VA
Helper II
Helper II

Hi,

Sorry, unable to upload pbix file, pasting the values below.

Note: I need Standard Deviation for 21 months from which ever date I select. In current scenario selected date is Jan-22
 

Datermv
Jun-203
Sep-2013
Oct-201
Nov-205
Dec-207
Jan-216
Feb-213
Mar-214
Apr-217
May-211
Jun-214
Jul-213
Aug-211
Sep-212
Oct-211
Nov-211
Dec-214
Jan-227

for the month of Jan-22, I had calculated Standard Deviation manually and '3.17' as result.

I used calendar table as well.

johnt75
Super User
Super User

Try

Standard Dev prev 6 months =
VAR MaxDate =
    MAX ( 'Date'[Date] )
VAR StartDate =
    EOMONTH ( MaxDate, -7 ) + 1
VAR DatesToUse =
    CALCULATETABLE (
        VALUES ( 'Date'[Year month] ),
        DATESBETWEEN ( 'Date'[Date], StartDate, MaxDate )
    )
VAR Result =
    STDEVX.P ( DatesToUse, COALESCE ( [Sum of sales], 0 ) )
RETURN
    Result

This assumes that you are including dates in the visual. If you just want to show data as at today then set a visual level filter so that the date is today.

Hi,

Thanks for replying

 

I tried same query with different month number {EOMONTH (MaxDate, -7)+1} and for all of them the result is 0.

Could you please share pbix file.

 

Thanks

can you share some sample data ?

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