Let σ be an operator mean in the sense of Kubo and Ando. If the representation function fσ of σ satisfies fσ(t) p ≤ fσ(t p ) for all p > 1, then σ is called a pmi mean. Our main interest is the class of pmi means (denoted by P M I). To study P M I, the operator mean σ, whereinis considered in this paper. The set of such means (denoted by GCV ) includes certain significant examples and is contained in P M I. The main result presented in this paper is that GCV is a proper subset of P M I.In addition, we investigate certain operator-mean classes, which contain