Figure 3

The output of the linear discriminant analysis. (A) The LDA scatterplot displays clear separation of the ependymoma (n = 18), medulloblastoma (n = 36) and pilocytic astrocytoma (n = 24). The decision boundaries, shown by the solid line, define the regions of the plot for each tumor type. (B) The loadings for the first discriminant function. The metabolites with more negative loadings are important for medulloblastoma classification, whilst metabolites with more positive loadings are important for pilocytic astrocytoma classification. (C) The loadings for the second discriminant function. Metabolites with more positive loadings are important for separating ependymoma from the other two tumor types. Abbreviations – GABA, gamma-aminobutyric acid; GPC, glycerophosphocholine; NAA, N-acetylaspartate; PCh, phosphocholine.