Quantifying Proportional Variability

Quantifying Proportional Variability

Real quantities can undergo such a wide variety of dynamics that the mean is often a meaningless reference point for measuring variability. Despite their widespread application, techniques like the Coefficient of Variation are not truly proportional and exhibit pathological properties. The non-parametric measure Proportional Variability (PV) [1] resolves these issues and provides a robust way t...

Quantifying temporal variability in population abundances

Understanding variability of population abundances is of central concern to theoretical and applied evolutionary ecology, yet quantifying the conceptually simple idea has been substantially problematic. Standard statistical measures of variability are particularly biassed by rare events, zero counts and other ‘non-Gaussian’ behaviour, which are often inappropriately weighted or excluded from an...

Quantifying Variability in the Alaskan Black Spruce

Synchrony: quantifying variability in space and time

1. There is growing recognition that linking patterns to their underlying processes in interconnected and dynamic ecological systems requires data sampled atmultiple spatial and temporal scales. 2. However, spatially explicit and temporally resolved data sets can be difficult to analyze using classical statistical methods because the data are typically autocorrelated and thus violate the assump...

Quantifying Rapid Variability in Accreting Compact Objects

I discuss some practical aspects of the analysis of millisecond time variability X-ray data obtained from accreting neutron stars and black holes. First I give an account of the statistical methods that are at present commonly applied in this field. These are mostly based on Fourier techniques. To a large extent these methods work well: they give astronomers the answers they need. Then I discus...