2D companion to the 3D prototype fidelity ladder: the same probability-of-detection (POD) model, read off a live defect map and a scrolling cost-vs-confidence chart instead of a rendered bracket. Every fidelity stage — paper mockup, digital CAD model, 3D-printed part, functional build — resolves hidden design flaws at a different rate; higher fidelity reveals more per round but costs more and takes longer.
P(detect one round) = 1 − e^(−k · r)
k = stage inspection-power constant
r = team-rigor multiplier (0.5× – 2.0×)
The defect injection rate slider seeds N hidden defects at fixed positions in the map (4–24). Each Run Test Round gives every still-hidden defect an independent Bernoulli trial at that stage's detection probability; found defects turn green permanently. Cost and time accumulate per round at the current stage's rate:
Paper: k=0.15 $5/round 0.5 day/round
Digital CAD:k=0.35 $40/round 1 day/round
3D-Print: k=0.65 $150/round 2 days/round
Functional: k=1.10 $600/round 4 days/round
- Fidelity stage buttons — change the detection-power constant k used by the next test round, and the cost/time it charges per round.
- Team rigor slider — scales k, modelling more careful (or rushed) inspection at any given fidelity.
- Defect injection rate — how many hidden flaws were designed into this build; more seeded defects means more rounds (and more cost) needed to reach the same confidence.
- Confidence — the fraction of seeded defects already found; the real-world proxy for "how sure are we this design is ready to ship".
This is the actual trade-off product teams reason about when deciding how far to push a prototype before committing to tooling: catching a flaw on paper costs a sketch; catching the same flaw after tooling a functional unit can cost weeks and thousands of dollars.