[R] How is the relation between Frequency and Counts in hist/density defined?

[Bert Gunter]

... Which makes the cumulative (discrete) distribution 1, as it should be.

-- Bert

On Mon, May 23, 2011 at 7:59 AM, Tal Galili <tal.galili at gmail.com> wrote:
> Thanks Richard!
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> On Mon, May 23, 2011 at 5:56 PM, <Richard.Cotton at hsl.gov.uk> wrote:
>
>>
>> > In order to do this I can use the relation between count and density, but
>> I
>> > would like to know if there is a way for me to predict it upfront.
>>
>> In the code for hist.default, you'll see the line
>>
>> dens <- counts/(n * diff(breaks))
>>
>> > Here is an example:
>> >
>> > set.seed(242)
>> > z = rnorm(30)
>> > hist_z <- hist(z)
>> > hist_z$counts / hist_z$density # the relation is 15
>>
>> In your example, n is 30, and the breaks are evenly spaced every 0.5.
>>
>> Regards,
>> Richie.
>>
>> Mathematical Sciences Unit*
>> **HSL* <http://www.hsl.gov.uk/contact-us.htm>*
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-- 
"Men by nature long to get on to the ultimate truths, and will often
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-- Maimonides (1135-1204)

Bert Gunter
Genentech Nonclinical Biostatistics