“…. , −1, then for a causal PARMA (p, q) process the covariance matrix k,i is non-singular for every k 1 and each i. Anderson et al [5] show that if EX t = 0 and k,i is nonsingular for each k 1, then the one-step predictorsX i+k , k 0, and their mean-square errors v k,i , k 1, are given by…”