In 2009, we published a paper in which we showed how three independent sources of data indicated that, rather than being a unidimensional measure of perceived usability, the System Usability Scale apparently had two factors: Usability (all items except 4 and 10) and Learnability (Items 4 and 10). In that paper, we called for other researchers to report attempts to replicate that finding. The published research since 2009 has consistently failed to replicate that factor structure. In this paper, we report an analysis of over 9,000 completed SUS questionnaires that shows that the SUS is indeed bidimensional, but not in any interesting or useful way. A comparison of the fit of three confirmatory factor analyses showed that a model in which the SUS's positive-tone (odd-numbered) and negative-tone (even-numbered) were aligned with two factors had a better fit than a unidimensional model (all items on one factor) or the Usability/Learnability model we published in 2009. Because a distinction based on item tone is of little practical or theoretical interest, we recommend that user experience practitioners and researchers treat the SUS as a unidimensional measure of perceived usability, and no longer routinely compute Usability and Learnability subscales.

Revisiting the factor structure of the system usability scale

Since its introduction in 1986, the 10-item System Usability Scale (SUS) has been assumed to be unidimensional. Factor analysis of two independent SUS data sets reveals that the SUS actually has two factors --- Usable (8 items) and Learnable (2 items --- specifically, Items 4 and 10). These new scales have reasonable reliability (coefficient alpha of .91 and .70, respectively). They correlate highly with the overall SUS (r = .985 and .784, respectively) and correlate significantly with one another (r = .664), but at a low enough level to use as separate scales. A sensitivity analysis using data from 19 tests had a significant Test by Scale interaction, providing additional evidence of the differential utility of the new scales. Practitioners can continue to use the current SUS as is, but, at no extra cost, can also take advantage of these new scales to extract additional information from their SUS data. The data support the use of "awkward" rather than "cumbersome" in Item 8.

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The Factor Structure of the System Usability Scale

In 1992, DeLone and McLean suggested that the dependent variable for information systems (IS) research is IS Success. Their research resulted in the widely cited DeLone and McLean (D&M) IS Success Model, in which System Quality, Information Quality, Use, User Satisfaction, Individual Impact, and Organizational Impact are distinct, but related dimensions of IS success. Since the original IS Success Model was published, research has developed a better understanding of IS success. Meanwhile, comprehensive and integrative research on the variables that influence IS success has been lacking. Therefore, we examine the literature on the independent variables that affect IS success. After examining over 600 articles, we focused our attention on integrating the findings of over 140 studies. In this research, we identify 43 specific variables posited to influence the different dimensions of IS success, and we organize these success factors into five categories based on the Leavitt Diamond of Organizational Change: ...

Information Systems Success: The Quest for the Independent Variables

Understanding factors affecting trust in and satisfaction with mobile banking in Korea: A modified DeLone and McLean's model perspective

Destination marketing organizations invest considerable amounts of money in the development of Web sites as part of their overall promotion efforts. With increasing pressure on their budgets, it becomes ever more important for these organizations to assess the effectiveness of their Web sites, evaluate the return on their investments, and derive feedback on necessary improvements. Web site evaluation measures have been proposed in many ways and various contexts over the past decade. The study presented in this article used a qualitative meta-analysis methodology to synthesize the diverse findings. A unified framework of commonly used Web site success factors emerged from the analysis and included a total of nine factors: (1) information quality; (2) ease of use; (3) responsiveness; (4) security/privacy; (5) visual appearance; (6) trust; (7) interactivity; (8) personalization; and (9) fulfillment. Additional factors to further inform Web evaluation efforts were identified based on Werthner and Klein's dime...

Itay Avni

Papers

User satisfaction from commercial web sites: The effect of design and use