# Standard deviation of root mean square error

## Main Question or Discussion Point

I am comparing two RMS error time-series and I would like to generate error bars on the RMS results. I think the RMS error is a standard deviation of an assumed zero mean process, and I have the gut feeling that this should be the standard deviation of the sample standard deviation. Is that correct? I would like to have a reference to cite on a paper I am writing at the moment, so if anyone knows of a useful reference I would appreciate some pointers.
Thanks in advance.

## Answers and Replies

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RMS deviation about the mean is not exactly the sample standard deviation because in computing the sample standard deviation you divide by n-1 instead of n. For large enough samples the difference is not important.

Hi mXSCNT,
Yes thanks for pointing that out. The sample sizes are large.
How about the confidence intervals of the RMS values? Any clues in how to calculate them?