stdevIf
Based on a conditional statement, the stdevIf function calculates the
			standard deviation of the set of numbers in the specified measure, grouped by the chosen
			dimension or dimensions, based on a sample. 
Syntax
stdevIf(measure, conditions)
Arguments
- measure
- 
						The argument must be a measure. Null values are omitted from the results. Literal values don't work. The argument must be a field. 
- condition
- 
						One or more conditions in a single statement.