Re: quartiles

*To*: mathgroup at smc.vnet.net*Subject*: [mg18224] Re: [mg18214] quartiles*From*: David Withoff <withoff at wolfram.com>*Date*: Thu, 24 Jun 1999 14:24:11 -0400*Sender*: owner-wri-mathgroup at wolfram.com

> I am working with some statistics problems and have a question about finding > quartiles for a set of data > > salaries = > {250000,100000,60000,60000,40000,40000,40000,40000,25000,20000,20000,20000, > 18000,16000,16000} > > Quartiles[salaries] > > {20000,40000,55000} > > The upper quartile should be the median of the numbers above the median, so > why is it 55000? > 250000,100000,60000, > 60000, > 40000,40000, 40000 > > Does Mathematica use some algorithm to get rid of outliers before finding > quartiles, or does it eliminate the median from the data set before finding > the quartiles, .....? > > The set of data I used as an example was taken from the math text I am using > and the answer the text supplies, and the answer I think I should get, is > different from the one Mathematica gets. I would appreciate any advice on this! > > Tom De Vries A discussion of the definition of Quartiles, and some alternate definitions, can be found in http://support.wolfram.com/Kernel/Symbols/Statistics/DescriptiveStatistics/Quartiles.html You can also get definitive information about these definitions by looking in the Statistics`DescriptiveStatistics` package, as the programming is straightforward. There are several definitions of quartiles that are in common use. Dave Withoff Wolfram Research