“…Further results on unbiased estimation of both kinds of effects were obtained, among others, by Goldberger [4], Henderson ([8], [9]), Harville [6], Rao [19], Jiang [10], Liu et al [16] and Tian [27]. Synówka-Bejenka and Zontek ( [25], [26]) have dealt with admissibility of linear estimators of fixed and random effects in some linear models. To get a characterization, they have shown that the problem of admissibility for a linear function of fixed and random effects is equivalent to the problem of admissibility for a linear function of the expected value only, in another properly defined linear model (called the dual model; see Section 3 for more details).…”