Motivated by marine ecological data on species abundance, with the record of subsamples, two problems are investigated in this paper, assuming the Ewens–Pitman sampling formula: One is the prediction of the number of new species if the catch is continued, and the other is how the number of...

The joint distribution of ordered (or unordered) frequencies of a sample from random proportions is the Donnelly-Tavaré-Griffiths formula (or the Ewens sampling formula) if and only if the size-biased permutation of the random proportions has the GEM distribution.

A Bonferroni-type inequality by Tan and Xu (1989) is extended, and proved by a simple method. The stringency of the extended inequality is also confirmed.