Abstract
The study of the sum of two independent phase-type (PH)-distributed variables, each of them being asso- ciated with a Markovian process with one absorbing state, is considered in this paper. The distribution function of the variable sum is computed, obtaining a new PH-distributed function of higher order. As the order increases in the new function, the exponential function of a block upper triangular matrix is calculated in terms of its respective blocks to reduce the dimension of the problem. The obtained results are applied to bladder carcinoma data.
