Behavioral psych + Choice Architecture — nudge design for onboarding, retention, conversion
Thaler-Sunstein nudge theory + Cialdini influence + Fogg behavior model + EAST framework (Easy / Attractive / Social / Timely) for product behavior design. Onboarding completion, retention curves, upsell conversion — every hypothesis built on a bias (defaults, loss aversion, social proof, anchoring, scarcity), A/B-tested, ethics-guarded (no dark patterns).