[R] Help: Beanplots calculating wrong average

[Tom Wainwright]

Hi Michael,

Looking at the help for beanplot(), note that the 'log' option defaults to 
'auto' which means the function will automatically log-transform data like 
yours.  This also implies that the mean it shows is the geometric mean, not the 
arithmetic mean.  As you note, the transformation doesn't affect the median.

If you don't want this behavior, I think setting log="" will do the trick.

Hope this helps.

	Tom Wainwright

On 11/24/2009 03:52 AM, Michael Hopgood wrote:
> Hi there,
>
> I have a set of data that looks like this:
>
> As1988<-c(1254.0, 22.0, 4.2, 1081.0, 35.0, 6.0, 1772.0,  192.0,  7.6)
>
> The mean of this (as calculated by R) is: 485.9778
>
> The median of this (as calculated by R) is:  35
>
>
>
> If I then make a beanplot(As1988), I find that the beanline (average) is now
> 77.68561 while the beanline (median) is 35.39739 (using the locator function
> to check the graph and log axis).
>
>
>
> While I can understand the small discrepancy of the median(mouse hovering
> over the line), I am at a loss to explain the huge difference between the
> means. Is this a flaw in the package or is there something I am missing?
>
>
>
> My gut feeling is that the log scales are affecting the calculations
> somehow.
>
>
>
> Sincerely,
>
> Michael Hopgood
>
>
>
>
> 	[[alternative HTML version deleted]]
>
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-- 
Tom Wainwright
NOAA Northwest Fisheries Science Center
Newport, Oregon
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