Code for forthcoming manuscript: Zero-inflation and overdispersion increase uncertainty in paleoecological studies of predation

Abstract for forthcoming manuscript:

The effects of overdispersion and zero-inflation (e.g., poor model fits) can result in misinterpretation in studies using count data. These effects have not been evaluated in paleoecological studies of predation and are complicated by preservational bias and time-averaging in death assemblages. We develop a hierarchical Bayesian framework and apply it to a predator-prey case study to illustrate the potential effects of overdispersion and zero inflation on counts of specimens and predation traces from biased, time-averaged paleoecological data.

Estimates of predation frequencies are underestimated when zero inflation is ignored, and this effect is likely compounded by removal of individuals and predation traces via preservational bias. Time-averaging likely reduces zero inflation via accumulation of rare taxa and events; however, it increases the uncertainty in comparisons between assemblages by introducing variability in sampling effort. That is, there is an analytical cost with time-averaged count data, manifesting as broader confidence regions. Ecological inferences in paleoecology can be strengthened by accounting for the uncertainty inherent to paleoecological sampling processes.