Fig. 3

Schema for ontologically grouped differential analysis. Example query human digestive tract versus bacterial metabolomes. a All BinBase samples with metadata that ontologically map to (Human, Digestive System without Disease) were compared to samples that mapped to (Bacteria Cells without Disease). b Such ontology-based summary queries yield a set of biological metadata combinations that are then subjected to pairwise differential analysis. c For each compound, pairwise differential analysis yields a matrix of p-values and a matrix of fold changes that can be conservatively described by the maximum p-value and minimum fold-change, respectively. Therefore, only one point is visualized per compound in downstream volcano plots