System Usability Scale Formula as Alternative for Calculating Composite Score of Likert-type Items
Since its conception, Likert Scales have been used extensively in various fields. There are many ways to describe data obtained with Likert scales. In Human Factors research, System Usability Scale (SUS) is a widely adapted Likert Scale instrument to assess the usability of various products and...
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| Main Authors: | , , |
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| Format: | Conference or Workshop Item |
| Language: | English |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://ir.unimas.my/id/eprint/12016/1/ICSSBE2015_IEEE_Donald.pdf http://ir.unimas.my/id/eprint/12016/ |
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| Institution: | Universiti Malaysia Sarawak |
| Language: | English |
| Summary: | Since its conception, Likert Scales have been used
extensively in various fields. There are many ways to describe data
obtained with Likert scales. In Human Factors research, System
Usability Scale (SUS) is a widely adapted Likert Scale instrument
to assess the usability of various products and systems.
Researchers often have the tendency to modify SUS to fit their
context of use, leading to various versions of SUS. Calculation of
the composite score for SUS instrument does not involve
computation of arithmetic mean/sum and re-coding of statements.
SUS formula obtains the score for each Likert-type items and
convert them into a single scale range from 0 to 100. Although SUS
is a popular instrument, there is no formula introduced to
facilitate the calculation of scale. This article aims to introduce a
formula to facilitate the calculation of various versions of SUS with
different number of items, number of positive and negative
statements, as well as scale size. Although primarily meant for SUS
practitioners, the formula presented can be used for any
instrument adapting Likert-type items should the researchers
decide to transform responses into 0-100 scale instead of
computation of mean or sum for various statistical analyses. The controversial computation of mean for Likert Scales has been subjected to decades of debate. This article demonstrates an alternate method to calculate composite score of Likert-type items based on calculation of SUS. Results show the formula yield the same results and perfect relationship with mean and sum for various tests, indicating it can be used as an alternative to mean
and sum as a composite score of Likert-types items. |
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