Some random variables, such as counts or incomes, assume only nonnegative values, while a normally distributed random variable do assume negative values. So transform the nonnegative variable by a logarithm before taking the average. (+/ % #)&.(^. @: >:)0 9 99 9
--- Den man 19/10/09 skrev J. Patrick Harrington <[email protected]>: > Fra: J. Patrick Harrington <[email protected]> > Emne: Re: [Jprogramming] "median" considered inaccurate? > Til: "Programming forum" <[email protected]> > Dato: mandag 19. oktober 2009 03.46 > > In processing astronomical images (e.g., Hubble), there > will be cosmic ray > hits (a single or cluster of pixels) with very high counts. > So to set the > background level, the median will not be strongly affected > by a few such > pixels, but the mean would be rendered useless. Just one > example of > where the the median is quite useful. > > > > > Patrick > > On Mon, 19 Oct 2009, Sherlock, Ric wrote: > > Yes, for example the median is a better measurement of > central location than the mean for skewed distributions > (incomes, test results). > > > >> From: [email protected] > >> > >> Tukey did show that median and quantiles are often > much more stable > >> than average.( f.e median polish and median > smoothing in general) > >> > >> ------------------- > >>> From: Bo Jacoby > >>> We are solving a problem which should not be > solved. The advantage > >> of Median and Quantiles, as opposed to > Arithmetical Mean and Standard > >> Deviation, is that they can be evaluated without > computing. Having a > >> computer at hand, this argument vanishes. > >>> > >>> --- Den s?n 18/10/09 skrev Fraser Jackson > >>> > >>>> Statistical programs have a range of > >>>> alternatives for the quantile function. > >>>> The following script embodies forms > >>>> considered in a useful survey paper some > years ago. It > >>>> requires further > >>>> functions to answer Devon's question but > >>>> does include some options worth > considering. > >>>> > >>>> NB. Quantile functions > > > > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > -----Inline-vedhæftet fil følger----- > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm Trænger du til at se det store billede? Kelkoo giver dig gode tilbud på LCD TV! Se her http://dk.yahoo.com/r/pat/lcd ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
