biostatistics

When designing a case-control study to investigate differences in microbial composition, it is fundamental to assess the sample sizes needed to detect an hypothesised difference with sufficient statistical power. Our application includes power calculation for (i) a recoded version of the two-sample generalised Wald test of the “HMP” R-package for comparing community composition, and (ii) the Wilcoxon-Mann-Whitney test for comparing OTU-specific abundances between two samples (optional).

The effect of adherence to statin therapy on cardiovascular mortality: quantification of unmeasured bias using falsification end-points

Background: To determine the clinical effectiveness of statins on cardiovascular mortality in practice, observational studies are needed. Control for confounding is essential in any observational study. Falsification end-points may be useful to determine if bias is present after adjustment has taken place.

Initial community evenness has been shown to be a key factor in preserving the functional stability of an ecosystem, but has not been accounted for in previous modelling studies. We formulate a model that allows the initial evenness of the community to be varied in order to investigate the consequent impact on system diversity. We consider a community of four interacting bacterial species, and present a stochastic, spatial individual-based model simulating the ecosystem dynamics. Interactions take place on a two-dimensional lattice.