[R] Quartiles and Inter-Quartile Range

[Peter Ehlers]

eeramalho wrote:
> 
> Thank you David. I got it now.
> 
> Maybe you can help again.
> 
> I am typing the following code to draw a QQ plot but the line does not look right?
> 
> *******************
> qqnorm(cbiomass)
> 
> qqline(cbiomass)
> ***********************
> the graph looks very different from the graph generated by SAS.

There are two possibilities:
1. you need to use the argument 'datax = TRUE'
2. SAS is wrong

You might also have a look at the qq.plot() function
in package 'car'.

  -Peter Ehlers

> 
> Thank you again.
> 
> Emiliano.
> 
> Date: Fri, 22 Jan 2010 21:32:26 -0800
> From: ml-node+1213199-1966337867 at n4.nabble.com
> To: eeramalho at hotmail.com
> Subject: Re: Quartiles and Inter-Quartile Range
> 
> 
> 
> It's looks like you think that type=2 are the 'true' quantiles, but the default method in R is type=7
> 
> 
> You might want to look at ?stats::quantile
> 
> 
> hth
> 
> david freedman
> 
> 
> 
> 
> 
> View message @ http://n4.nabble.com/Quartiles-and-Inter-Quartile-Range-tp1145817p1213199.html
> 
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-- 
Peter Ehlers
University of Calgary