Differentially abundant taxa between lean and obese human gut microflora.

For the phylum, class, and genus levels (mean percentage��s.e., p-value��0.01) we successfully re-established the major result of Ley et al., and uncovered a new difference within Actinobacteria. Both Firmicutes and Actinobacteria have significantly higher relative abundances in obese people, while Bacteroidetes make up a higher proportion of the gut microbiota in the lean population. Results reveal Clostridia as the primary component of the differential abundance observed within Firmicutes, and Bacteroidetes and Actinobacteria classes explain the differential abundance observed within the corresponding phyla. Using this p-value threshold, we expect less than one false positive among these results. The last four columns display the computed p-values for different statistical methods, including Metastats and the overdispersion methods of Lu et al. (Log-t) and Robinson and Smyth (NB). These results reveal NB and Student's t-test to be overly-conservative.