[Octave-bug-tracker] [bug #57606] geometric distribution documentation

[Tony Richardson]

URL:
  <https://savannah.gnu.org/bugs/?57606>

                 Summary: geometric distribution  documentation
                 Project: GNU Octave
            Submitted by: amrichardson
            Submitted on: Wed 15 Jan 2020 04:54:51 PM UTC
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Documentation
                  Status: None
             Assigned to: None
         Originator Name: Anthony Richardson
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 5.1.0
        Operating System: Any

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Details:

The help documentation for the geo* statistical functions says that the random
variable X is the total number of trials until the the first success.  The
actual functions returns results that assume that X is the number of failures
until the first success (there is on off by one difference).  The
documentation needs to be changed to be consistent with the implementation.

You will find both definitions in the literature.  The current Octave
implementation seems to be consistent with the MATLAB implementation (based on
my looking at the MATLAB documentation).

For geopdf the help documentation says:

The geometric distribution models the number of failures (X-1) of a Bernoulli
trial with probability P before the first success (X).

I believe this should be changed to:

The geometric distribution models the number of failures (X) of a Bernoulli
trial with probability P before the first success.





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