Self-Reported Metrics - Measuring the User Experience: Collecting, Analyzing, and Presenting Usability Metrics - page 140

DO YOU NEED BOTH POSITIVE AND NEGATIVE STATEMENTS
IN SUS?
As shown in Figure 6.8 , half of the statements in SUS are positive and half are negative.
While some argue that this approach keeps participants “on their toes,” others have
argued that it also seems to confuse some participants, perhaps causing erroneous
responses. Sauro and Lewis (2011) conducted a study in which they compared the
traditional version of SUS to an all-positive version. They found no significant difference
between mean SUS scores for traditional and all-positive versions. But in a review of 27
SUS data sets, they found evidence that 11% of the studies had some miscoding of SUS
data and 13% of the individual SUS questionnaires contained mistakes by users. They
suggest using an all-positive version of SUS to avoid some of those possible errors. If you
want to use the all-positive version, see Sauro and Lewis (2011) for an example.
6.4.3 Computer System Usability Questionnaire
Jim Lewis (1995), who developed the ASQ technique for post-task ratings, also
developed the Computer System Usability Questionnaire (CSUQ) to do an over-
all assessment of a system at the end of a usability study. The CSUQ is very similar
to Lewis's Post-Study System Usability Questionnaire (PSSUQ), with only minor
changes in wording. The PSSUQ was originally designed to be administered
in person, whereas CSUQ was designed to be administered by mail or online.
CSUQ consists of the following 19 statements to which the user rates agreement
on a seven-point scale of “Strongly Disagree” to “Strongly Agree,” plus N/A:
1. Overall, I am satisfied with how easy it is to use this system.
2. It was simple to use this system.
3. I could effectively complete the tasks and scenarios using this system.
4. I was able to complete the tasks and scenarios quickly using this system.
5. I was able to efficiently complete the tasks and scenarios using this system.
6. I felt comfortable using this system.
7. It was easy to learn to use this system.
8. I believe I could become productive quickly using this system.
9. The system gave error messages that clearly told me how to fix problems.
10. Whenever I made a mistake using the system, I could recover easily and
quickly.
11. The information (such as online help, on-screen messages, and other
documentation) provided with this system was clear.
12. It was easy to find the information I needed.
13. The information provided for the system was easy to understand.
14. The information was effective in helping me complete the tasks and
scenarios.
15. The organization of information on the system screens was clear.
16. The interface of this system was pleasant.
17. I liked using the interface of this system.