---
title: "Stdev (MDX) | Microsoft Docs"
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ms.date: "03/02/2016"
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  - "STDEV"
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  - "kbMDX"
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  - "Stdev function [MDX]"
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---
# Stdev (MDX)
[!INCLUDE[tsql-appliesto-ss2008-xxxx-xxxx-xxx_md](../includes/tsql-appliesto-ss2008-xxxx-xxxx-xxx-md.md)]

  Returns the sample standard deviation of a numeric expression evaluated over a set, using the unbiased population formula (dividing by n-1).  
  
## Syntax  
  
```  
  
Stdev(Set_Expression [ ,Numeric_Expression ] )  
```  
  
## Arguments  
 *Set_Expression*  
 A valid Multidimensional Expressions (MDX) expression that returns a set.  
  
 *Numeric_Expression*  
 A valid numeric expression that is typically a Multidimensional Expressions (MDX) expression of cell coordinates that return a number.  
  
## Remarks  
 The **Stdev** function uses the unbiased population formula, while the [StdevP](../mdx/stdevp-mdx.md) function uses the biased population formula.  
  
## Example  
 The following example returns the standard deviation for Internet Order Quantity, evaluated over the first three months of calendar year 2003, using the unbiased population formula.  
  
```  
WITH MEMBER Measures.x AS   
   Stdev   
   ( { [Date].[Calendar].[Month].[January 2003],  
       [Date].[Calendar].[Month].[February 2003],  
       [Date].[Calendar].[Month].[March 2003]},  
    [Measures].[Internet Order Quantity])  
SELECT Measures.x ON 0  
FROM [Adventure Works]  
```  
  
## See Also  
 [MDX Function Reference (MDX)](../mdx/mdx-function-reference-mdx.md)