Data Analysis -> Descriptive Statistics -> Standard Deviation, "other" result

[hansaaa]

Hi,

I am using the "Data Analysis" tool-pak that can be used in Excel, and, I have some questions about it.

At this moment, I will only ask one question:

Using Data Analysis -> Descriptive Statistics

produces a set of, well, Descriptive Statistics (oh, wonder ).

It ALSO produces, among some others, the Standard Deviation of a set of input Data.

For example, I am using a simple "testing" set of Data:

{1000, 1000, 2, 5, 1}.

What is happening is:

The Standard Dev the Data Analysis -> Descriptive Statistics tool produces is:

546.2639

HOWEVER, when I compute the Standard Dev of the set on my calculator, using formula:

sd.jpg

I get a standard Deviation of:

488.593.

How is this accounted for? Or, in other words:

Why does my calculator (where I input, and, calculated, all the five deviations/variations manually, applying the formula given, just now), give a different result?

Thanks!

hansaaa

[XOR LX]

Hi again,

How much do you know about Standard Deviation? Perhaps you should start with this site:

http://www.mathsisfun.com/data/stand...-formulas.html

Basically the STDEV formula in Excel is equivalent to Sample Standard Deviation. If your dataset is the entire population, you should be using STDEVPA which will give you your desired result.

[hansaaa]

Yep, I just realized that as well. The standard deviation in this case was a "sample" standard dev, using some "heuristic" to estimate it.

If I use STDEV.P(), I get the desired result, as expected!

Thanks for your help, XOR!

[XOR LX]

No worries. Glad to see someone's using Excel to do some proper maths!