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thanks! Very interesting. Is the standard deviation still useful for some of the other distributions you mentioned, that look vaguely Gaussian?
by logicallee 9y ago
thanks! Very interesting. Is the standard deviation still useful for some of the other distributions you mentioned, that look vaguely Gaussian?
- thanatropism 9y agoThe standard deviation is defined as E[(X-EX)^2] If EX = infinity but X is finite with prob > 0, the standard deviation will be infinite too.
- R_haterade 9y agoYou're referring to the square root of the second moment about the mean. The short answer is yes, it's always useful, provided you have an estimator. Check out Chebyshev's inequality. Just don't start talking about it to your pointy-haired boss. You'll get fired.
- logicallee 9y agothanks. but what does your last line, about the boss mean?
- R_haterade 9y agoThat this sort of knowledge is often uninteresting to non-technical types. I'm pretty jaded at this point.
- dbaupp 9y agoFor the specific example of the Cauchy distribution, the standard deviation isn't defined.