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I have derived the following response time data for a performance test I am running:

Min - 8sec Max - 284sec Average - 28sec Standard Deviation - 27sec

What does the standard deviation say about the response time data distribution? When you say low/high standard deviation, what does this actually mean? Is this in comparison to the Average/Min/Max?

I know what standard deviation is and how it's computed. I'm just not sure how to tell if it is high or low.

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    Aren't terms like "high" or "low" just a matter of subjective judgement? The data you have seem to suggest that time is very roughly speaking 28sec +/- 27 sec, so in a very naive sense you expect the results to usually fall between 1sec and 60sec. I'd say it's rather high deviation, but I suppose it depends on the characteristic of a problem.2012-12-17

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If you take your cues from the financial industry, you can use the coefficient of variation (CV), which is the standard deviation / mean. This formula is used to normalize the standard deviation so that it can be compared across various mean scales.

As a rule of thumb, a CV >= 1 indicates a relatively high variation, while a CV < 1 can be considered low.

Some references to usage as "rule of thumb"

http://www.readyratios.com/reference/analysis/coefficient_of_variation.html

http://www.mhnocc.org/forum/index.php?t=msg&goto=234&

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    I have listed a couple of refere$n$ces above.2012-12-20