Essence
Prioritization answers "what to do first" when ideas outnumber hands. Decide by a transparent criterion, not by who shouts loudest. Any model is a tool for discussion and focus, not "truth in numbers" — the number sharpens the argument but doesn't replace judgment.
Formulas & matrices
RICE = (Reach × Impact × Confidence) / Effort. Impact scale 3/2/1/0.5/0.25; Confidence as %.
ICE = Impact × Confidence × Ease (quick).
MoSCoW: Must / Should / Could / Won't.
Kano: basic (expected) / linear (more=better) / delighters (wow).
value/effort — a 2×2 quick filter.
Worked RICE example
A. Tag filter: Reach 4000, Impact 2, Conf 80%, Effort 2w → (4000×2×0.8)/2 = 3200.
B. Cloud sync: Reach 2500, Impact 3, Conf 50%, Effort 8w → (2500×3×0.5)/8 ≈ 469.
C. Dark theme: Reach 6000, Impact 1, Conf 100%, Effort 1w → 6000.
Rank: C > A > B. Start with dark theme (cheap, broad, confident); sync is valuable but costly/uncertain → prototype first to raise Confidence.
When to use
RICE/ICE to compare many ideas; MoSCoW for release scope; Kano for "must vs wow"; value/effort for a quick start.
Pitfalls
False precision; ignoring Confidence; optimistic Effort; everything Must; only basics (no wow); scoring for scoring's sake.