The recent paper [27] provides a statistical analysis for efficient detection of signal components when missing data samples are present. Here we focus our attention to some complex-valued discrete random variables X l (m, N ) (0 ≤ l ≤ N − 1, 1 ≤ M ≤ N ), which are closely related to the random variables investigated by LJ. Stanković, S. Stanković and M. Amin in [27]. In particular, by using a combinatorial approach, we prove that for l = 0 the expected value of X l (m, N ) is equal to zero, and we deduce the expression for the variance of the random variables X l (m, N ). The same results are also deduced for the real part U l (m, N ) and the imaginary part V l (m, N ) of X l (m, N ), as well as the facts that the kth moments of U l (m, N ) and V l (m, N ) are equal to zero for every positive integer k which is not divisible by N/ gcd(N, l). Moreover, some additional assertions and examples concerning the random variables X l (m, N ), U l (m, N ) and V l (m, N ) are also presented.