aus_fas Posted January 20, 2009 Share Posted January 20, 2009 Hi I have a distribution for which I would like to use median say M. The problem is that I do not know how to define some range based on M+3 [math]\sigma[/math]. Is there some kind of variance related to median ? Link to comment Share on other sites More sharing options...
timo Posted January 21, 2009 Share Posted January 21, 2009 Since you have the distribution why would you not simply calculate the variance from it? Link to comment Share on other sites More sharing options...
DJBruce Posted January 22, 2009 Share Posted January 22, 2009 If it is a binomial distribution then: [math]\mu=np[/math] [math]\sigma=(np(1-p))^{2}[/math] so [math]\sigma=(\mu(1-p))^{2}[/math] and in a normal distribution the medians is equal to the mean so you should be able to relate the two. Hope this helped. Link to comment Share on other sites More sharing options...
stereologist Posted March 23, 2009 Share Posted March 23, 2009 In general if your distribution is symmetrical, then the median and mean are the same. Remember that the 3 sigma rule relates to normal distributions. If you do not have a normal distribution then the 99.7% does not apply. The percent might be higher or lower - it all depends on your data. Link to comment Share on other sites More sharing options...
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