Questionnaires for Assessing Perceived Usability of Websites 223 · · · Helpfulness: 0.7 Learnability: 0.74 Global: 0.9 With about four items per subscale, these values are a bit on the low side, but still indicative of a reasonable level of reliability, especially for large-sample studies. The WAMMI developers may well have decided to trade off some reliability to dramatically reduce the length of the questionnaire and the time required to complete it. SUPR-Q (Standardized Universal Percentile Rank Questionnaire) Description of the SUPR-Q The SUPR-Q (Sauro, 2011b) is a rating scale designed to measure perceptions of usability, credibility/ trust, appearance, and loyalty for websites. Like the WAMMI, the SUPR-Q provides relative rankings expressed as percentages, so a SUPR-Q percentile score of 50 is average (roughly half the websites evaluated in the past with the SUPR-Q have received better scores and half received worse). In addi- tion to this global comparison, the SUPR-Q normative database (with data from over 200 websites and over 5000 users) allows comparison of scores with a subset of 100 other websites and 18 indus- tries. The price of a commercial license for the SUPR-Q is $499 for the limited license and $1999 for