
244 Pricing in General Insurance
respect to the Gaussian approximation, is that it is not symmetric, but the other problems
(difculties in modelling the tail, difculties in quantifying the errors) remain.
17.3 Numerical Quasi-Exact Methods
Numerical methods for calculating the aggregate loss distribution simply attempt to cal-
culate the convolution integrals directly using discrete mathematics, using the fact that
integrals can be approximated as a nite sum; for example, Riemann’s construction men-
tioned in Box 17.1. All these methods require replacing both the severity distribution f
X
(x)
and the aggregate loss distribution f
S
(x) with a disc ...