Observed data for σ_B plotted as: (a) distribution of σ_B binned and averaged by the bin count in T_⊥/T_∥–β_∥ parameter space. The instability thresholds for the oblique fire-hose (OF) and mirror-mode (M) instabilities are shown as labelled. (b) PDFs of σ_B for oblique fire-hose unstable (magenta), mirror-mode unstable (blue), and stable (green) points in our dataset. The vertical lines denote the ensemble mean [ ⋅ ] of each dataset.