Let X1, X2, and X3 be
independent random variables and let Z1= X1+ X3 and Z2= X2+ X3. It is known
that if the characteristic functions of Xk, k = 1,2,3, do not vanish then the
distribution of (Z1,Z2) determines the distributions of X1, X2, and X3 up to a shift.
The aim of this paper is to prove a result of a similar nature using sums of a random
number of random variables. We shall use ∼ for “has the same distribution as,”
r.v. for “random variable,” ch.f. for “characteristic function,” and p.g.f. for
“probability generating function.”