-----Original Message----- From: Deepayan Sarkar [mailto:[EMAIL PROTECTED] Sent: Monday, September 17, 2007 5:10 PM To: Nair, Murlidharan T Cc: [EMAIL PROTECTED] Subject: Re: [R] MAD
On 9/17/07, Nair, Murlidharan T <[EMAIL PROTECTED]> wrote: > > I am calculating the median absolute deviation using mad function, and > it tends to ignore the parameter constant=1, when I am calculating it > for x=seq(1:5). Am I missing something here? > > x<-seq(1:5) > mad(x)# gives [1] 1.4826 > mad(x, constant=1)# gives [1] 1 > #Here is the long form > dev.from.median<-abs((x-median(x))) > dev.from.median # Gives [1] 2 1 0 1 2 > sum(dev.from.median) # Gives [1] 6 > sum(dev.from.median)/length(x) # Gives [1] 1.2 > # The long form does not match the output from the function > > # When x<-seq(1:10) they match > x<-seq(1:10) > dev.from.median<-abs((x-median(x))) > sum(dev.from.median)/length(x) # Gives 2.5 > mad(x, constant=1) # Gives 2.5 > #The long form matches the output from the function > > Did I miss anything here? yes; mad := Median (not mean) absolute deviation (from the median, by default). -Deepayan Indeed, its median and that what I am calculating in the long form. So, what is that you found I was doing differently? May be I missed your point. Thx../M ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
