Long story short, Standard deviation and variance are different ways of representing the same thing (variance/deviation – google it for more info). But trying to work out how much the data varies based on only a few pieces of data is difficult, so an error factor is added in that helps out. This error factor gets smaller and smaller with more data so that with very large data sets the population and sample functions will return almost identical results.

When to use which one? Rule of thumb is you rarely or never use the population one because you almost never have, know or able to measure every measurement from all possible measurements.

Let’s say you are mearsuring the height of children in a class. They are “samples” of children of their age/type and therefore use the sample functions. You shouldn’t use the population function unless you can measure and have a record of all children of ages that could be in your class across all time.

In fact, very few times will you ever have the entire population of data so very few times will use use the population functions, and if you did have all the data chances are the sample functions would return the same results.

As for Mode and other statistical functions, I offer an sql server SQL Math library that provides those abilities. sqladmintools.com

]]>i need to know the statistical fucvtion in choosing course in college??

tnx!!

]]>i need to know the statistical in choosing course in college??

tnx!!

]]>Here is another sample to explain relationships between SQL Server statistic functions:

USE AdventureWorks;

GO

SELECT STDEVP(Bonus) ‘Standard Deviation for the Population’,

STDEV(Bonus) ‘Standard Deviation’,

VAR(Bonus) ‘Variance’,

STDEV(Bonus)* STDEV(Bonus) ‘VAR via STDEV’,

VARP(Bonus) ‘Variance for the Population’,

STDEVP(Bonus)* STDEVP(Bonus) ‘VARP via STDEVP’,

VAR(Bonus)*(COUNT(Bonus)-1)/COUNT(Bonus) ‘VARP via VAR ‘

FROM Sales.SalesPerson;

GO

Thanks

Oleg

i know about this function but my requirement is some what complicated

i have one table which include two thing one is district and the county now i want all county list not records group by district.

ex

District1

coun1, coun2, coun3

District2

coun1, coun2, coun3

So how can i do such thing

:) manish (: