  A method based on the classical principal component analysis leads to
demonstrate that the role of co-authors should give a h-index measure to a
group leader higher than usually accepted. The method rather easily gives what
is usually searched for, i.e. an estimate of the role (or "weight") of
co-authors, as the additional value to an author papers' popularity. The
construction of the co-authorship popularity H-matrix is exemplified and the
role of eigenvalues and the main eigenvector component are discussed. An
example illustrates the points and serves as the basis for suggesting a
generally practical application of the concept.
