[R] sciplot question

Manuel Morales Manuel.A.Morales at williams.edu
Sun May 24 15:02:02 CEST 2009


You define your own function for the confidence intervals. The function
needs to return the two values representing the upper and lower CI
values. So:

qt.fun <- function(x) qt(p=.975,df=length(x)-1)*sd(x)/sqrt(length(x))
my.ci <- function(x) c(mean(x)-qt.fun(x), mean(x)+qt.fun(x))

lineplot.CI(x.factor = dose, response = len, data = ToothGrowth,
    ci.fun=my.ci)

Manuel

On Fri, 2009-05-22 at 18:38 +0200, Jarle Bjørgeengen wrote:
> Hi,
> 
> I would like to have lineplot.CI and barplot.CI to actually plot  
> confidence intervals , instead of standard error.
> 
> I understand I have to use the ci.fun option, but I'm not quite sure  
> how.
> 
> Like this :
> 
>  >  qt(0.975,df=n-1)*s/sqrt(n)
> 
> but how can I apply it to visualize the length of the student's T  
> confidence intervals rather than the stdandard error of the plotted  
> means ?
> 
-- 
http://mutualism.williams.edu



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