Raluca Budiu

Raluca Budiu is Director of Research at Nielsen Norman Group, where she consults for clients from a variety of industries and presents tutorials on mobile usability, designing interfaces for multiple devices, quantitative usability methods, cognitive psychology for designers, and principles of human-computer interaction. She also serves as editor for the articles published on Raluca coauthored the NN/g reports on tablet usability, mobile usability, iPad usability, and the usability of children's websites, as well as the book Mobile Usability. She holds a Ph.D. from Carnegie Mellon University.


Articles and Videos

  • Working Memory and External Memory

    People have very limited ability to keep information in their working memory while performing tasks, so user interfaces should be designed accordingly: to minimize memory load. One way of doing so is to offload items to external memory by showing them on the screen.

  • How to Fit Big Tables on Small Screens

    No matter your screen size, some data tables will be too big for the screen. This problem is particularly common on mobile devices. Simple interaction techniques can help, but you may need to offer users more advanced features for information hiding and column reordering.

  • How Many Participants for Quantitative Usability Studies: A Summary of Sample-Size Recommendations

    40 participants is an appropriate number for most quantitative studies, but there are cases where you can recruit fewer users.

  • Why 5 Participants Are Okay in a Qualitative Study, but Not in a Quantitative One

    Qualitative usability testing aims to identify issues in an interface, while quantitative usability testing is meant to provide metrics that capture the behavior of your whole user population.

  • UI Modes and Modals

    Modes can be a hidden state and lead to user errors. But they can also make a user interface more efficient by allowing the same action to have different results, depending on the situation.

  • Confidence Intervals, Margins of Error, and Confidence Levels in UX

    A confidence-interval calculation gives a probabilistic estimate of how well a metric obtained from a study explains the behavior of your whole user population.

  • Direct Manipulation in User Interfaces

    Direct manipulation is an interaction technique in graphical user interfaces where users move depictions of objects around and get immediate feedback about their actions and the outcome of these actions.

  • Why You Cannot Trust Numbers from Qualitative Usability Studies

    Qualitative usability studies have few users and variable protocol; numbers obtained from such studies are likely to poorly reflect the true behavior of your population due to large measurement errors.

  • Common Ground and UX

    Any efficient communication requires that communication partners establish and rely on common ground so that they can take communication shortcuts.

  • PM and UX Have Markedly Different Views of Their Job Responsibilities

    A survey of people in user experience and product management shows that these professionals disagree on who should be responsible for many key tasks, like doing discoveries and early design.