Browse Content by Topic

Usability Testing (19)

Sample Size (18)

UX (12)

Usability (11)

SUS (11)

Task Time (11)

Survey (11)

Questionnaires (9)

Usability Problems (9)

Rating Scale (8)

Statistics (7)

Remote Usability Testing (7)

Net Promoter Score (7)

Usability Metrics (6)

Problem Discovery (6)

Satisfaction (6)

Task Completion (5)

Confidence Intervals (5)

User Research (3)

Summative (3)

Loyalty (3)

Heuristic Evaluation (3)

SUPR-Q (3)

Formative Testing (3)

Regression Analysis (3)

Clicks (2)

PhD (2)

Benchmarking (2)

Mobile Usability Testing (2)

SEQ (2)

Keystroke Level Modeling (2)

Problem Severity (2)

Cognitive Walkthrough (2)

Margin of Error (2)

Credibility (2)

Card Sorting (2)

Qualitative (2)

Information Architecture (2)

Sampling (2)

Crowdsourcing (2)

Z-score (1)

UI Disasters (1)

Interval (1)

Marketing (1)

Top Box Scoring (1)

Monte Carlo (1)

Return on Investment (1)

Ethonographic Research (1)

Geometric Mean (1)

Key Drivers (1)

Median (1)

Methods (1)

Evidence Based Design (1)

A/B Testing (1)

iPhone (1)

Analytics (1)

Lean UX (1)

Correlation (1)

Errors (1)

Reliability (1)

Think Aloud (1)

Post-Task Ratings (1)

Quality Assurance (1)

Task Times (1)

Task Failure (1)

Salaries (1)

Ordinal (1)

Completion Rate (1)

Problem Discovery Topics

How common are usability problems?

Jeff Sauro • September 29, 2010

Usability problem frequencies from 24 usability tests show that users are almost ten-times more likely to encounter a usability problem in a business application than a website. Users are about half as likely to encounter a problem in consumer software than a business application.[Read More]

Will five users really find 85% of all usability problems?

Jeff Sauro • May 6, 2010

The sample size formula for finding usability problems only works for a specific set of users and closed-ended tasks. With five users you will only find the more obvious problems.[Read More]

Do severe problems affect more users than trivial ones?

Jeff Sauro • March 25, 2010

While testing with five users might reveal 85% of problems that impact 31% of users (given a set of tasks and user-type), it doesn't mean you're finding 85% of the critical problems. Assume that the severity of a problem is not related to how often it occurs.[Read More]

Why you only need to test with five users (explained)

Jeff Sauro • March 8, 2010

For finding usability problems with an interface, testing with five users is fine to find problems that affect 31% to 100% of all users. If a problem is more elusive (affects fewer than 31% of users) then you need to increase your sample size. This sample size does not apply to comparing designs or generating a precise estimate of completion rates or task-times.[Read More]

If 1 of 5 users has a problem in a usability test will it impact 1% or 20% of all users?

Jeff Sauro • February 1, 2010

Insurance companies do it, drug companies do it and so should usability testers. When you observe a problem from a small sample test, it is unlikely the problem only affects a tiny percentage of users.[Read More]

Deriving a Problem Discovery Sample Size

Jeff Sauro • March 8, 2004

Shows the history and computation of deriving a sample size for discovering problems in an interface.[Read More]