Standard Diviation

[ask]

I have a set of data for student's score for 2 years. i will get the standardard deviation of list of student on picked day. how to do that?  Output will look like this. 

Name	Score	Standard deviation
Name 1	768
Name 2	273
Name 3	190
Name 4	96
Name 5	94
Name 6	96
Name 7	98
Name 8	98
Name 9	96
Name 10	86

[Anonymous]

The simpliest way would be to create a Card visual and place the Score column into the Values box.  As long as the Score column is of type number, you'll be able to choose Standard Deviation from the list of aggregations.

Something like this:

Alternatively, you could create a measure using either one of these functions:
https://msdn.microsoft.com/en-us/library/gg492207.aspx
https://msdn.microsoft.com/en-us/library/gg492150.aspx

[ask]

@Anonymous  the column of "STANDARD DEVIATION OF WELLNESS SCORE", I use the built in function of power bi which is the simply way you mentioned.,

The column of Score STDEV.P  comes from the calculation : Score SD = CALCULATE(STDEV.P(data[Score]),ALLEXCEPT(data, data[Score], data[Name]))

are they supposed to be the same?

Name	Score	Standard deviation of Wellness Score	Score STDEV.P
NAME 1	768	0	8
NAME 2	273	0	18
NAME 3	190	0	38
NAME 4	96	0	7
NAME 5	94	0	14
NAME 6	96	0	8
NAME 7	98	0	1
NAME 8	98	0	5
NAME 9	96	0	2
NAME 10	86	0	8

[v-ljerr-msft]

Hi @ask,

Based on my test, the build-in standard deviation function should be similar to just using the STDEV.P function without any other filters like below. 

Score SD = STDEV.P(data[Score])

Regards

[ask]

@v-ljerr-msft have you tried to pick the specific date. for example every wednesday for the past 2 years?  How to do that?

[v-ljerr-msft]

Hi @ask,

The formula below should work. 

Score SD =
CALCULATE (
    STDEV.P ( data[Score] ),
    FILTER ( data, WEEKDAY ( data[Date] ) = 4 && YEAR ( data[Date] ) >= 2015 )
)

Regards

[ask]

@v-ljerr-msft How about to check the dynamic date instead of wednesday, that might be Tuesday, Monday, etc, and also dynamic name selected.

Score SD =
CALCULATE (
    STDEV.P ( data[Score] ),
    FILTER ( data, WEEKDAY ( data[Date] ) = 4 && YEAR ( data[Date] ) >= 2015 )
)

[v-ljerr-msft]

Hi @ask,

1. Add [Year], [MonthName], [WeekName] column to your table if you have them yet.

Year = YEAR(data[Date]) 

MonthName = FORMAT(data[Date],"MMMM") 

WeekName = FORMAT(data[Date],"DDDD")

2. Simply use the formula below to create a measure for 'Score SD', then you should be able to use the [Year], [MonthName], [WeekName], [Name] column as Slicers on the report to dynamically get the standard deviation of list of student on picked day. 

Score SD =
CALCULATE (
    STDEV.P ( data[Score] )
)

Regards

[ask]

Name	Score	Standard deviation of Wellness Score	Score STDEV.P
NAME 1	768	0	8
NAME 2	273	0	18
NAME 3	190	0	38
NAME 4	96	0	7
NAME 5	94	0	14
NAME 6	96	0	8
NAME 7	98	0	1
NAME 8	98	0	5
NAME 9	96	0	2
NAME 10	86	0	8

Hi @v-ljerr-msft  the table doesn't have Year, Month, Week. Only have Name, Score,  Date as shown above

[v-ljerr-msft]

Hi @ask,

I don't see any Date column in your sample table above. Anyway, it doesn't matter.

1. Add [Year], [MonthName], [WeekName] column to your table if you have them yet.

Year = YEAR(data[Date]) 

MonthName = FORMAT(data[Date],"MMMM") 

WeekName = FORMAT(data[Date],"DDDD")

---

I knew your table doesn't have Year, Month, Week. As I have mentioned in Step 1: You need to add them first!!(just use the formula I have provided above)

Regards

[ask]

@v-ljerr-msftMy requirement doesn't allow me to create slicer. Any way to calculate the SD by each name, by specific date?