Symptoms
Assume that you calculate the standard deviation of the same data that contains exactly 10 items by using the STDEV.P function and the STDEVX.P function separately. You notice the result that is returned by STDEV.P differs from the result that is returned by STDEVX.P. In this case, the result that is returned by STDEVX.P is incorrect.
Resolution
This problem was first fixed in the following cumulative update for SQL Server:
Cumulative Update 6 for SQL Server 2014 Service Pack 1
About cumulative updates for SQL Server
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
Latest cumulative update for SQL Server 2014
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminology Microsoft uses to describe software updates.