Question about histogram

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[R] Question about histogram

Longe 

to:

r-help

01/13/2011 03:11 PM

Sent by:

r-help-bounces at r-project.org

Dear list,

I'm new to R, please bear with my silly questions.  I'm trying to get an 

understanding of why the results I get from a call to hist() are not as 
I thought I would get.  When I use the parameter freq=FALSE, I think the 

plot will contain bars that none of them is larger than 1, because 
they're probabilities.  But for my code, the bars exceeded 1.

The actual data seems immaterial.  I tried with dummy data:

 > hist(runif(1000), freq=FALSE)

and the histogram includes bars well over 1 in height.  The man page 
says that freq=FALSE produces densities, so that the total area is 1. 
Clearly if all the values are between 0 and 1, as is the case here, some 

of the bars stand out above 1, for the area to be 1.  I thought that it 
is the sum of the bar heights that would be 1, so that the bars reflect 
probabilities for each interval, rather than densities.  So, the answer 
to my question would be "because it's densities, not probabilities", but 

then the question is, why densities and not probabilities?

Regards,
L.