# [R] Plotting confidence intervals

phii m@iii@g oii phiiipsmith@c@ phii m@iii@g oii phiiipsmith@c@
Sun Dec 8 14:58:40 CET 2019

```Thanks so much Jim. Yes, this is giving me what I want.

Philip

On 2019-12-08 05:00, Jim Lemon wrote:
> Hi Philip,
> This may be a starter:
>
> attach(airquality)
> heights <- tapply(Temp,Month,mean)
> temp_sd<-tapply(Temp,Month,sd)
> lower <- tapply(Temp,Month,function(v) t.test(v)\$conf.int[1])
> upper <- tapply(Temp,Month,function(v) t.test(v)\$conf.int[2])
> library(plotrix)
> barp(heights,ylim=c(0,100),names.arg=month.abb[5:9],
>  main="Air quality (May-Sep)",xlab="Month",ylab="Temperature")
> dispersion(1:5,y=heights,ulim=upper,llim=lower,intervals=FALSE)
> ci95<-seq(-1.96,1.96,length.out=40)
> norm_curve<-rescale(dnorm(ci95),c(0,0.4))
> for(i in 1:5)
>  polygon(c(i-norm_curve,i+norm_curve),
>   c(heights[i]+ci95*temp_sd[i],heights[i]+rev(ci95*temp_sd[i])))
>
> Jim
>
> On Sun, Dec 8, 2019 at 8:18 PM <phil using philipsmith.ca> wrote:
>> >> I want to show little bell curves on my bar chart to illustrate the
>> >> confidence ranges. The following example from Paul Teetor's "R
>> >> Cookbook"
>> >> does what I want, but shows I-beams instead of bell curves. The
>> >> I-beams
>> >> suggest uniform, rather than normal distributions. So I am looking
>> >> for a
>> >> way to plot normal distribution curves instead.

```