Validation Phase

The design stage where solutions are tested with real users to confirm they work.

stellae.design

Process

The Validation Phase tests design solutions with users to verify they solve the defined problem effectively. Methods include moderated usability testing, unmoderated remote testing, A/B testing, accessibility audits, expert heuristic reviews, and concept testing. Validation answers: Does this work? Can users complete tasks? Do they understand the interface? Are there accessibility issues? The ROI is enormous — fixing a problem in design costs ~1x, in development ~10x, and after launch ~100x. Validation should be iterative: test → refine → retest.

Why It Matters

The validation phase is the stage in the design process where assumptions, prototypes, and solutions are tested against real user behavior and business requirements before committing to full development. Skipping validation leads to costly rework, misaligned features, and products that solve the wrong problems. Effective validation reduces risk by surfacing usability issues, technical constraints, and market mismatches when they are cheapest to fix.

Real-World Examples

Moderated usability test on checkout flow

A team conducts five moderated usability sessions with a clickable prototype of a redesigned checkout flow, recording task completion rates and time-on-task. Three of five participants struggle with the same address-entry step, revealing a clear design problem before any code is written. The team iterates on the design and retests, confirming the fix before handing off to engineering.

A/B test validating a new onboarding sequence

After launching a redesigned onboarding flow to 10% of new users, the team compares activation rates against the control group over two weeks. The new flow shows a statistically significant improvement in seven-day retention, validating the design direction with quantitative evidence. The team proceeds to a full rollout with confidence backed by data.

Counter-example

Skipping validation due to schedule pressure

A product team bypasses usability testing to meet a launch deadline, relying on internal reviews and stakeholder opinions to approve the design. Post-launch analytics reveal that users abandon the core workflow at twice the expected rate, and the team spends three sprints rebuilding the feature. The time saved by skipping validation is dwarfed by the cost of rework and lost user trust.

Role-Specific Guidance

Common Mistakes

• Teams often treat validation as a single gate at the end of the design phase rather than an ongoing practice woven throughout the process. Another common error is testing with colleagues or stakeholders instead of representative users, which produces biased feedback that confirms existing assumptions. Running tests without predefined success criteria makes it difficult to make objective decisions, leading to subjective debates about whether results are good enough.