Consolidate categories (domain logic first, bad rate second)

Merge rare or similar categories into fewer, meaningful groups and verify the bad rate of each merged group. Concepts: Category consolidation; rare levels; risk ordering; small-sample caution Project A: Your merges: checking 4 → 3 (negative / non_negative / no_account), credit_history 5 → 3, purpose 10 → 4 (new car / used car / home-related / other), savings, employment, debtors (co-applicant + guarantor), install plans (bank + stores), job (employed / unemployed), credits (one / more), age → 5 bands. Keep savings 'unknown' as its own group. Project B: weather_description dozens of labels → 4–5 weather types (clear, clouds, rain, storm, fog).