Christopher J Costello | PubMed Health

PubMed2003

Testing the power law model for discrete size data.

It is sometimes claimed that different types of size data in biology follow a power law. Here, a formal statistical test of the power law for discrete size data is described. The test is based on embedding the power law in the nonparametric family of distributions for which frequency is nonincreasing with size. A parametric bootstrap is used to assess significance. The test is applied to four data sets concerning the frequency of genera of different sizes. The power law is rejected in three out of four cases.

Body Constitution↗

PubMed2003

On the pattern of discovery of introduced species.

Introductions of nonindigenous species can have significant effects. It is commonly claimed that the rate of species introductions to the United States has increased over time. This claim is based in part on the increasing rate of discoveries of introduced species. This discovery rate is influenced by factors other than the introduction rate. These include the sampling rate and population growth in the introduced species. In this article, we show that the discovery rate can increase even when there is no increase in either the introduction rate or the sampling rate. This suggests that the basis for some claims regarding an increasing rate of introductions may be invalid.

Ecosystem↗