Fig. 5: Effect of scaling bias on multivariate analysis of an OrbiSIMS mouse testis image.

a PCA scores (PCs 1-7, 34, 39, 77, 81) of the mouse testis dataset using various scaling methods (purple=positive, green=negative, the absolute maximum in the scale is clipped for better contrast, the scales vary from +/− of this for each PC). b Assumed variance vs. mean plots for different scaling methods compared to WSoR model. c WSoR loadings of PCs 2–7. Intensity distributions of d C₅H₄N₅⁻, e C₂₅H₄₇SO₁₀⁻, f C₄₁H₇₉O₁₂S⁻, g C₁₀H⁻, h C₁₂H⁻, i C₄H₆N₃O⁻, j C₄H₈N₃O₂⁻, k C₁₈H₃₅O₂^- and l KCl₂⁻. The WsoR PC 7 scores map (and equivalent for other scaling and ion distributions) has been cropped to a smaller number of pixels to facilitate visualisation.