Qualitative early-warning performance of CT-eProber for systemic financial crises. (a) Distribution of 88 systemic financial crises across countries (left) and years (right) over the period 1870–2016, where the colour denotes the number of crises. (b)–(f) Schematic illustration of one-, two-, three-, four- and five-year-ahead early warning tasks for systemic financial crises, together with the corresponding receiver operating characteristic (ROC) curves.