Designing without research is guessing. A designer who skips user research is making assumptions about what people need, how they think, and what they will do — assumptions that are sometimes right but often expensive to be wrong about. User research is how UX designers replace guessing with evidence. Here are the six methods you will use most, and when to reach for each one.
1. User interviews
User interviews are one-on-one conversations where you ask open-ended questions to understand how someone thinks, what they care about, and how they currently solve a problem. They are qualitative — you are looking for patterns in how people describe their experience, not statistically significant data. The most important rule: ask about behavior, not opinion. "Tell me about the last time you tried to do X" produces more useful data than "would you use a feature that did Y?"
2. Surveys
Surveys give you quantitative data at scale. They are useful for validating patterns you identified in interviews, measuring attitudes across a large population, and tracking changes over time. The trap with surveys is asking leading questions or measuring what is easy to ask rather than what matters. Write questions that are specific, unambiguous, and behavior-focused. A survey of thirty people rarely produces reliable insights; aim for at least one hundred responses before drawing conclusions.
3. Usability testing
Usability testing means watching real users try to complete specific tasks with your product — and staying quiet while they do. The goal is to identify where users get confused, stuck, or frustrated. Even five users completing a task will reveal the most significant usability problems. You do not need a lab or expensive software: a video call with screen sharing, a prototype or live product, and a task list is enough to run a meaningful test.
4. Card sorting
Card sorting is a technique for understanding how users mentally organize information — which is essential for designing navigation and information architecture. You give participants a set of cards (each representing a piece of content or a feature) and ask them to group the cards in a way that makes sense to them, then name each group. The results reveal the mental models your users already have, which should drive your navigation structure rather than your own internal logic.
5. A/B testing
A/B testing compares two versions of a design by showing each to a different segment of real users and measuring which performs better on a defined metric. It is quantitative and requires statistical significance to be meaningful — which means you need enough traffic and enough time to run a valid test. A/B testing is most powerful for optimizing existing flows, not for discovering what to build. It tells you which of two options works better; it does not tell you why, or whether either option is the right approach.
6. Heuristic evaluation
A heuristic evaluation is an expert review of a product against a set of established usability principles — most commonly Nielsen's 10 usability heuristics, which include things like visibility of system status, error prevention, and consistency. It requires no participants and can be done quickly, making it useful early in a project or when time and budget are limited. The limitation is that it reflects expert judgment, not actual user behavior — so it works best as a complement to, not a replacement for, user testing.
When to use each
Use interviews early, when you are trying to understand the problem space. Use surveys to validate patterns across a larger population. Use usability testing on prototypes or live products to catch friction before or after launch. Use card sorting when designing or auditing navigation. Use A/B testing to optimize high-traffic flows. Use heuristic evaluation as a fast, low-cost audit at any stage. Research should inform design, not delay it — even a single user interview before a major design decision is more valuable than none. To learn UX design end to end, explore the UX designer track on NewRoleKit.