# Standard Deviation Issue

#### Runehakl

##### New member
Hello everyone!

I'm just trying to find out the standard dev between 2 numbers for a work project. A number in a population (17.35%) and the mean of said population (14.65%). An online calc yields an STDEV of 1.35% whilst Excel (using the sample stdev formula) yields 1.90%.

I'm not sure if the online calc takes into consideration that it's a sample because when I divided by N-1 (or 1.... is this even right?) I got 1.90%.

Am I even doing this right?

Thank you all in advance for the help. Any and all is appreciated.

#### tkhunny

##### Moderator
Staff member
Are you using stdev() or stdevp() or stdeva() or stdevpa() or stdev.p() or stdev.s()? Makes a difference.

Read those definitions carefully and make sure you are selecting the right one for your needs.

#### tkhunny

##### Moderator
Staff member
They should not all give the same answer. Something fishy about that. 1.35 is assuming your 17.35 and 14.65 constitute the entire population. 1.90 assumes they are a sample from the population. Anyway, if you just pick two values, why do you think it's a random sample - something that would be required for a Standard Deviation to be meaningful?

" standard dev between 2 numbers for a work project."

I'm struggling with this. There is only one deviation "between 2 numbers". This makes the concept of a standard deviation less that interesting.

Perhaps, if you could supply the entire problem statement?