Using STDEV in a text box vs SQL query in dataset.

[bessebo]

Hi,
I am trying to resolve an issue I am having with performing a STDEV in sql code vs putting the STDEV(...) function in a text box in a group footer in SSRS. For very large data sets (let's called large over 100,000 data points) I can at times get back high standard deviations when I use the STDEV that is the function within SSRS. But when I use the STDEV function in SQL and put that in the dataset query the number comes back fine (same answer as if you use STDEV in Excel).
I was wondering if anyone has had this issue within SSRS 2005. I spent about 4 hours testing this yesterday and I cannot figure out why this is happening. I figured it had something to do with the grouping. It is befuddling me...

Best,
Bessebo

 

[xlbo]

Best bet is to keep calcs in the SQL. SSRS is best at presenting with fairly lightweight calcs. In other words. If you can calc it elsewhere then do so!

Rgds, Geoff

We could learn a lot from crayons. Some are sharp, some are pretty and some are dull. Some have weird names and all are different colours but they all live in the same box.

Please read FAQ222-2244 before you ask a question

 

[bessebo]

Have you seen this phenomenon in your reports? It still makes no sense to me...

 

[xlbo]

Sorry but no - as I stated, I tend to do the vast majority of processing SQL side rather than RS side

Rgds, Geoff

We could learn a lot from crayons. Some are sharp, some are pretty and some are dull. Some have weird names and all are different colours but they all live in the same box.

Please read FAQ222-2244 before you ask a question

 

[bessebo]

OK thanks Geoff. I use Reporting Services every day to create reports for customers. I was forced, in this case, to perform all calculations in the SQL, particularly the stdev. I have even looked out there for bugs in 2005 but cannot find anything. This is a really strange phenomenon. I want to look a little more into it to see the difference based on amount of data points. I think the larger the data set the larger the discrepancy in the calculation for stdev in the report vs the sql...

Thanks,
Bob