[R] Histogram

[Achim Zeileis]

On Tue, 25 May 2004 12:27:40 +0200 Cristian Pattaro wrote:

> Dear all,
> 
> I have a surprising problem with the representation of frequencies in
> a histogram.
> 
> Consider, for example, the R code:
> 
> b<-rnorm(2000,3.5,0.3)
> hist(b,freq=F)
> 
> When I plotted the histogram, I expected that values in the y-axis
> (the probability) varied between 0 and 1. Instead, they varied within
> the range 0-1.3.

The y-axis gives the density not the probability!

And the density you are sampling from has

R> dnorm(3.5, mean = 3.5, sd = 0.3)
[1] 1.329808

so you shouldn't be surprised by this.
Z

> Have you got any suggestion for obtaining a correct graph with 
> probability within the range 0-1?
>
> Thank you very much!
> 
> Bests
> /Cristian/
> 
> =============================================
> Cristian Pattaro
> =============================================
> Unit of Epidemiology & Medical Statistics
> Department of Medicine and Public Health
> University of Verona
> 
> http://biometria.univr.it
> cristian at biometria.univr.it
> =============================================
> 
> 
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