[R] dnorm() lead to a probability >1

[Dirk Eddelbuettel]

On Fri, Oct 31, 2003 at 02:40:15PM -0500, Marc Belisle wrote:
> Howdee,
> 
> One of my student spotted something I can't explain: a probability >1 vs a
> normal probability density function.

The integral has to be 1 --- but dnorm doesn't compute that. 

You were probably looking for pnorm(), and it will give you 0.5 for all
those cases (where x==mean) as you'd expect.

Hth,  Dirk


> > dnorm(x=1, mean=1, sd=0.4)
> [1] 0.9973557
> 
> > dnorm(x=1, mean=1, sd=0.39)
> [1] 1.022929
> 
> > dnorm(x=1, mean=1, sd=0.3)
> [1] 1.329808
> 
> > dnorm(x=1, mean=1, sd=0.1)
> [1] 3.989423
> 
> > dnorm(x=1, mean=1, sd=0.01)
> [1] 39.89423
> 
> > dnorm(x=1, mean=1, sd=0.001)
> [1] 398.9423
> 
> Is there a bug with the algorithm?
> 
> Thanks,
> 
> Marc
> 
> ========================
> Marc B?lisle
> Professeur adjoint
> D?partement de biologie
> Universit? de Sherbrooke
> 2500 boul. de l'Universit?
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> 
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> 
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