 # Difference when calculating Standard Deviation in Excel and DAX

• Hi experts,

Not sure why I am getting different results when calculating standard deviation in Excel and DAX using the same data sample.

In Excel using STDEV.S(C9:N9) the result is 2176

 Mth_1 Mth_2 Mth_3 Mth_4 Mth_5 Mth_6 Mth_7 Mth_8 Mth_9 Mth_10 Mth_11 Mth_12 StDev 12118 8059 9180 6352 6863 6797 8548 7657 8845 7063 6352 2916 2176

Using DAX function STDEVX.S the result is 342

STD (12mth):=STDEVX.S(RawData,CALCULATE([Mth1]+[Mth2]+[Mth3]+[Mth4]+[Mth5]+[Mth6]+[Mth7]+[Mth8]+[Mth9]+[Mth10]+[Mth11]+[Mth12])) = 342

Gilly

• It would be clearer with a sample workbook, but I think you are doing two completely different calculations. Your Excel one is the standard deviation of the totals for each month, whereas your DAX one looks like the standard deviation for the total of all months for each row of your table.

Rory
Theory is when you know something, but it doesn’t work. Practice is when something works, but you don’t know why. Programmers combine theory and practice: nothing works and they don’t know why