Enterprise Risk Management Formula Book
Appendix A.5: Probability Distributions: Multivariate
probability distributions
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Multivariate normal (i.e. Gaussian) distribution
 
The multivariate probability distribution  where
 where  is a vector
of
 is a vector
of  elements
and
 elements
and  is an
 is an  non-negative
definite matrix has the following joint density function (where
 non-negative
definite matrix has the following joint density function (where  is the
determinant of V)
 is the
determinant of V)
 

 
The means of the individual marginal distributions are  where
 where  and the
covariance between the
 and the
covariance between the  ’th and the
’th and the  ’th
marginal distributions are
’th
marginal distributions are  where the
 where the  are the
elements of
 are the
elements of  . Its moment
generating function is
. Its moment
generating function is  and its
characteristic function is
 and its
characteristic function is  . The
multivariate normal distribution has as its copula the Gaussian copula.
. The
multivariate normal distribution has as its copula the Gaussian copula.
 
A bivariate random variable  follows a standard
bivariate normal distribution if it has
 follows a standard
bivariate normal distribution if it has  and
 and  . More
generally, a multivariate normal distribution is a standard multivariate normal
distribution if
. More
generally, a multivariate normal distribution is a standard multivariate normal
distribution if  and
a covariance matrix which is also a correlation matrix, i.e. where the variance
of each individual marginal distribution is 1.
 and
a covariance matrix which is also a correlation matrix, i.e. where the variance
of each individual marginal distribution is 1.
 
For numerical values of the cumulative distribution function
of the standard bivariate normal distribution see here.
 
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