[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Dinosaur-relevant article for you statistics gurus

M. Salicrú, S. Vives and J. Ocaña. In Press, Uncorrected Proof, Available
online 12 August 2004. Testing the homogeneity of diversity measures: a
general framework. Journal of Statistical Planning and Inference.  

We discuss the problem of testing the homogeneity of entropy (or diversity)
measures, as an extension of asymptotic results concerning the distribution
of a reasonable homogeneity statistic. The proposed improvements are based
upon corrections similar to those of Satterwhaitte and other authors. As an
alternative approach, we also consider a bootstrap procedure. The problem of
making multiple comparisons of diversity measures is considered, using
either an asymptotic or a bootstrap approach. The use of these methods is
illustrated using data, concerning the problem of the extinction of
dinosaurs. Finally, we present the results of a simulation study, to
determine the relative merits of these methods. The main conclusion is that
the corrections to the asymptotic theory and the bootstrap procedure show a
good balance between precision and moderate computational cost. 

This doesn't present anything really new or groundbreaking for paleontology,
but it does present another approach to dealing with the K-T extinction. The
authors reanalyze the data from the Sheehan et al. 1991 paper (the one which
concluded that the K/T extinction was sudden). 

In their presentation of the data, I'm pretty horribly confused (although if
I go back to the Sheehan paper, which I don't have with me at home, perhaps
it would clear things up. For instance, their data table gives a listing of
"Number of dinosaur species per family in three Cretaceous periods." The
periods are divided into Upper, Middle, and Lower. For ceratopsians, they
list 50 species in the upper, 53 in the middle, and 19 in the lower! I
wonder if they are talking about specimens, instead. Anyone have the Sheehan
paper handy to confirm this?