Hi, give a look to: http://www.itl.nist.gov/div898/handbook/eda/section3/eda35h.htm
it's the Grubbs' Test for Outliers. It is based on the assumption of normality of data. Other methods of outliers' could: Run-Sequence Plot Histogram Normal Probability Plot Box-plot Best Vito you wrote: Hi, this is both a statistical and a R question... what would the best way / test to detect an outlier value among a series of 10 to 30 values ? for instance if we have the following dataset: 10,11,12,15,20,22,25,30,500 I d like to have a way to identify the last data as an outlier (only one direction). One way would be to calculate abs(mean - median) and if elevated (to what extent ?) delete the extreme data then redo.. but is it valid to do so with so few data ? is the (trimmed mean - mean) more efficient ? if so, what would be the maximal tolerable value to use as a threshold ? (I guess it will be experiment dependent...) tests for skweness will probably required a larger dataset ? any suggestions are very welcome ! thanks for your help Philippe Guardiola, MD ===== Diventare costruttori di soluzioni Visitate il portale http://www.modugno.it/ e in particolare la sezione su Palese http://www.modugno.it/archivio/cat_palese.shtml ___________________________________ http://it.seriea.fantasysports.yahoo.com/ ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
