[R] Creating error bars in scatterplot() function (cars-Package)

[David Winsemius]

On Mar 30, 2011, at 5:10 PM, philsen wrote:

> Dear list,
> I am new to R and trying to create a grouped (four groups) scatter  
> plot with error bars (only in y-direction) using the scatterplot()  
> function from the car package.
> The code I am using for plotting the scatter plot is:
>
> scatterplot(a$s_profile~a$s_plot | a$group, data=a)
>
> which gives me a nice grouped scatter plot. However I have no idea  
> how to insert error bars. Using errbar() from the Hmisc Package  
> gives some unwanted results, e.g. adding new points with an offset  
> in xy(!?) even when specifying the xlim/ylim parameters.

Generally people use the arrows function for error bars when working  
in base graphics.

>
> Another problem is to move/orientate the plotted legend  
> individually, is there any possibility?
>
> I would appreciate your help in solving my problems.



David Winsemius, MD
Heritage Laboratories
West Hartford, CT