Message-ID: <1243170122.17053.17.camel@localhost.localdomain>
Date: 2009-05-24T13:02:02Z
From: Manuel Morales
Subject: sciplot question
In-Reply-To: <59824FB9-2C19-407A-8058-781CB01B867A@bjorgeengen.net>
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 Bj?rgeengen 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 ?
>
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