SYSTEM USABILITY SCALE: A VALIDITY AND RELIABILITY STUDY

Zafer Kadirhan
Middle East Technical University

Abdulmenaf Gul
Hakkari University

Ali Battal
Middle East Technical University

Abstract

The System Usability Scale (SUS), developed by Brooke (1996), was adapted into Turkish by Çağıltay (2011) with the name of Sistem Kullanılabilirlik Ölçeği. Having the ability to evaluate any system easily and quickly, SUS has been used in many usability studies successfully. Although the scale, consisting of 10 items, was considered as one factor when it was first developed, in many further studies it has been found that the scale was comprised of two factors. The main purpose of this study is to investigate the psychometric properties of the Turkish-adapted SUS in terms of validity and reliability. For this purpose, data were gathered from two different groups of 1100 individuals in two phases, 465 of whom were using a web based assessment and evaluation system (OSSI) and 635 were using the Education Information Network (EBA) system. In the first phase, exploratory factor analysis was performed with data collected from OSSI system and it was determined that the Turkish-adapted scale was composed of two factors; (1) Usable, (2) Learnable, similar to many previous studies in the literature. In the second phase, confirmatory factor analysis was performed using the data collected from EBA system, and the two-factor structure was confirmed with CFA. Reliability analyzes showed that the scale factors had Cronbach alpha values of .79 and .60, respectively, and these values were acceptable. It will be possible to obtain more reliable and meaningful results with the determined psychometric properties of SUS in the usability studies.

Keywords

System Usability, Usability Scale, Validity, Reliablity

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