The numbers behind the file — and where each one comes from

· Baymard Institute — Checkout Usability Research

· Baymard Institute — Mobile E-Commerce Usability

· Baymard Institute — E-Commerce Search Usability

· Baymard Institute — Cart Abandonment Rate Statistics

· Baymard Institute — Mobile Form Usability: Never Use Inline Labels

· Google, Deloitte Digital & fifty-five — Milliseconds Make Millions (site speed → revenue, 2020)

· Google / SOASTA — Page load time & bounce probability (2017)

· CXL Institute — Checkout Optimization & Trust Seals (original research)

· Stripe — Checkout flow design strategies

· Nielsen, J. (1994) — 10 Usability Heuristics

· Nielsen, J. (2006) — F-Shaped Pattern Reading on the Web

· NN/g (2017) — F-Shaped Pattern: Misunderstood, But Still Relevant

· NN/g — Scrolling and Attention

· NN/g — Error-Message Guidelines

· NN/g — Mobile Content Is Twice as Difficult

· NN/g — Trustworthiness on the Web

· NN/g — Icon Usability

· Penzo, M. (2006) — Label Placement in Forms (UXmatters eyetracking)

· Wroblewski, L. — Top, Right or Left Aligned Form Labels

· Jarrett, C. & Gaffney, G. (2009) — Forms That Work: Designing Web Forms for Usability, Morgan Kaufmann

· Silver, A. (2017) — Better Form Design: One Thing Per Page (Smashing)

· Wroblewski, L. (2011) — Mobile First, A Book Apart

· Hoober, S. (2013) — How Do Users Really Hold Mobile Devices? (UXmatters)

· Ingram, S. (2016) — The Thumb Zone: Designing for Mobile Users (Smashing)

· HTTP Archive — Web Almanac 2024 — Accessibility

· HTTP Archive — Web Almanac 2024 — Performance

· WebAIM — The WebAIM Million 2025 (accessibility of the top 1,000,000 home pages)

· W3C — WCAG 2.1 SC 1.4.3 Contrast (Minimum)

· W3C — WCAG 2.1 SC 2.5.5 Target Size

· W3C — WCAG 2.2 SC 2.4.11 Focus Appearance

· Apple — Human Interface Guidelines — Accessibility

· Google — Material Design 3 — Accessibility Basics

· Google — Material Design 3 — Type Scale Tokens

· Krug, S. (2000, rev. 2014) — Don't Make Me Think

· Spool, J. — The $300 Million Button

· Iyengar, S. S. & Lepper, M. R. (2000) — When Choice is Demotivating (JPSP)

· Scheibehenne, B., Greifeneder, R. & Todd, P. M. (2010) — Can There Ever Be Too Many Options? (JCR)

· Thaler, R. & Sunstein, C. (2008) — Nudge, Yale University Press

· Spiegel Research Center, Northwestern — How Online Reviews Influence Sales

· Laws of UX (Hick's Law and others)

· Thomke, S. (2020) — Building a Culture of Experimentation (HBR)

· Nielsen, J. (2000) — Jakob's Law (users expect your site to work like the others they know)

· Tesler, L. — Tesler's Law / Conservation of Complexity

· Postel, J. (1981) — Postel's Law / Robustness Principle (RFC 760/793)

· Ebbinghaus — Serial Position Effect

· Doherty, W. J. & Thadani, A. J. (1982) — The Economic Value of Rapid Response Time, IBM (the "Doherty threshold"; the discrete 400 ms figure is the popularized Laws-of-UX framing, not the paper's claim)

· Kahneman, D. et al. (1993) — Peak–End Rule ("When More Pain Is Preferred to Less")

· Nunes, J. C. & Drèze, X. (2006) — The Endowed Progress Effect, J. Consumer Research (car-wash field study: 34% completion with a head start vs 19% without); Kivetz, Urminsky & Zheng (2006) — Goal-Gradient (J. Marketing Research)

· Ariely, D. (2008) — Predictably Irrational, ch.1 — the decoy effect (Economist subscription: 84% vs 68% chose the target with a decoy present)

· Tversky, A. & Kahneman, D. (1974) — Judgment under Uncertainty: Heuristics and Biases (anchoring); effect-size caveat: Li (2025), Economic Inquiry

· Kahneman, D. & Tversky, A. (1979) — Prospect Theory / loss aversion (losses weigh ~2× gains; meta-analytic λ ≈ 1.95, Brown et al. 2024, JEL)

· Cialdini, R. — 7 Principles of Persuasion (reciprocity, authority, unity); Strohmetz et al. (2002), "Sweetening the Till," J. Applied Social Psychology

· NN/g — Banner Blindness Revisited (right-rail content drew ~0.8% of attention)

· W3C — SC 2.5.8 Target Size (Minimum) — 24×24 CSS px, AA

· W3C — SC 2.5.7 Dragging Movements — AA

· W3C — SC 2.4.11 Focus Not Obscured (Minimum) — AA

· W3C — SC 2.4.13 Focus Appearance (≥2px, ≥3:1 focused-vs-unfocused)

· W3C — SC 3.3.7 Redundant Entry — Level A

· W3C — SC 3.3.8 Accessible Authentication (Minimum) — AA

· W3C — SC 1.3.5 Identify Input Purpose (autocomplete tokens) — AA

· W3C — SC 4.1.3 Status Messages & SC 4.1.2 Name, Role, Value

· W3C — SC 2.4.4 Link Purpose (In Context) — Level A

· W3C — SC 1.4.11 Non-text Contrast (3:1 for UI & graphics) — AA

· WebAIM — Screen Reader User Survey #10 (~72% navigate a long page by its headings first)

· Nielsen, J. — Response Time Limits (0.1s / 1s / 10s)

· web.dev — Interaction to Next Paint (INP) ("good" ≤ 200ms)

· NN/g — Progress Indicators Make a Slow System Less Insufferable

· NN/g — Skeleton Screens 101

· NN/g — Error-Message Guidelines

· NN/g — Designing Empty States

· NN/g — Confirmation Dialogs (If Not Overused)

· NN/g — Placeholders in Form Fields Are Harmful

· NN/g — Reset and Cancel Buttons

· NN/g — How Little Do Users Read? (~20–28% of words) & Inverted Pyramid

· Simon Hearne — Optimistic UI Patterns (and the React useOptimistic docs)

· NN/g — Proximity Principle & Group Form Elements with White Space

· NN/g — Similarity Principle

· NN/g — Common Region: Containers Create Groupings

· NN/g — The Illusion of Completeness (false floors)

· Wroblewski, L. — Evaluating UIs with the Squint Test

· Wathan, A. & Schoger, S. — Refactoring UI: hierarchy via size + weight + color

· W3C — SC 1.4.1 Use of Color & Technique G183 (links: 3:1 + a non-color cue)

· Myndex — Why APCA (perceptual contrast; the WCAG 3 direction)

· Google — Material 3: how the color system works (HCT tone distance ≥40 ⇒ 3:1, ≥50 ⇒ 4.5:1)

· Google — Material dark theme (#121212 base, desaturate accents, elevation by overlay)

· MDN — oklch() / perceptual color

· Colour Blind Awareness — prevalence of color-vision deficiency (~8% of men, ~0.5% of women)

· web.dev — The most effective ways to improve Core Web Vitals (fetchpriority, unsized images, long tasks)

· web.dev — Browser-level image lazy loading (never lazy-load the LCP image)

· web.dev — Best practices for fonts (WOFF2 ~30% smaller; font-display)

· web.dev — Defer non-critical CSS & Optimize long tasks (>50ms)

· web.dev — Resource hints (preconnect)

· HTTP Archive — Web Almanac 2024 — Media (image-format adoption)

· Baymard — Avoid Splitting Single Input Entities (one "Full name" field)

· Baymard — Inline Form Validation (31% have none) & Auto-Format Card Number

· Baymard — Format Expiry Like the Physical Card (72% don't)

· Baymard — Getting Address Line 2 Right & Order-summary best practices

· Baymard — Perceived Security at Checkout (19% abandon over card-trust)

· web.dev — Payment & address form best practices; MDN — autocomplete tokens

· GOV.UK — Password input & Content design (plain language)

· Stripe — Checkout optimizations (Link lifts logged-in conversion >7%)

· EU — GDPR Art. 7(3) ("as easy to withdraw as to give consent") + EDPB Guidelines 05/2020; CNIL 2021 cookie-banner fines (reject must be as easy as accept)

· NN/g — Deceptive Patterns in UX; Brignull — deceptive.design

· FTC — Bringing Dark Patterns to Light (2022); ROSCA & FTC Act §5 (the 2024 "click-to-cancel" rule was vacated in 2025); EU Digital Services Act Art. 25