varBb {dbd} | R Documentation |
Variance of a beta binomial distribution.
Description
Calculate the variance of a random variable having a beta binomial distribution.
Usage
varBb(mo,...)
## S3 method for class 'mleBb'
varBb(mo,...)
## Default S3 method:
varBb(mo, s, size, ...)
Arguments
mo |
For the |
s |
Numeric scalar, greater than 0. The overdispersion parameter
of the distribution. (See the help for |
size |
Integer scalar specifying the upper limit of the “support”
of the beta binomial distribution under consideration. The support
is the set of integers |
... |
Not used. |
Details
For the "mleBb"
method, the single argument should really
be called (something like) “object
” and for the
default method the first argument should be called m
.
However the argument lists must satisfy the restrictions that
“A method must have all the arguments of the generic,
including ... if the generic does.” and “A method
must have arguments in exactly the same order as the generic.”
For the "mleBb"
method, the values of m
and s
are obtained from mo
, and size
is extracted from
the attributes of mo
.
The variance of a beta binomial distribution is readily calculable “by hand”. These functions are provided for convenience and to preserve parallelism with the db distribution.
Value
Numeric scalar equal to the variance of a beta binomial distributed random variable with the given parameters.
Author(s)
Rolf Turner r.turner@auckland.ac.nz
See Also
Examples
varBb(0.7,0.1,15)
varBb(0.7,400,15)
X <- hmm.discnp::Downloads
fit <- mleBb(X,size=15)
varBb(fit)