I myself looked for a camera some time ago and I found nothing. The fact is that the SUS was published as a "quick and dirty" free scale and that no one "recognizes" it in the same way that the Human Factors Research Group at UCC controls the SUMI.
More importantly, there is now a lot of data published on the English version of the SUS and its features that can help you plan and interpret the usability tests with this version (see references below). To my knowledge, no one has collected or published the same type of data for a German version. Apart from that, we really do not know how it compares to the English version and nothing helps to say that one translation is better than another.
Depending on your needs and the efforts you want to make, you can do one of three things:
- Just use a translation that makes you feel good. It should certainly be enough to see some differences between designs or products, which is the most important way to interpret SUS scores (absolute scores do not tell you much without a benchmark to which you can compare them ).
- Opt for the SUMI. It is a little older and longer and is not free, but there is an official German translation that will provide more information (it includes several more specific subscales in addition to overall satisfaction / perceived user-friendliness) . The wording of some items may seem awkward for some products, such as websites.
- Develop your own translation (and possibly publish it). The best solution for this type of thing is to ask one or more experts to translate the documents from English into German, then to the other experts to do a reverse translation to check if the meaning has not been translated. modified, revising translations if necessary. Then use this translation in a large user test (at least hundreds of participants and preferably different types of products), examine elements such as reliability and factor structure, compare them to publish data on the English version and check if certain elements have specific problems and need to be corrected or replaced.
Important documents on the English version of the SUS (next to the Brooke document already mentioned):
- Bangor, A., Kortum, P.T., & Miller, J.T. (2008). An empirical evaluation of the scale of use of the system. International Journal of Human-Computer Interaction, 24 (6), 574-594.
- Borsci, S., Federici, S. and Lauriola, M. (2009). On the dimensionality of the scale of use of the system: test of alternative measurement models. Cognitive treatment, 10 (3), 193-197.
- Lewis, JR & Sauro, J. (2009). Factorial structure of the system utilization scale. Proceedings of the International Human Computer Interaction Conference (HCII 2009), CA San Diego, USA.
- Sauro, J. & Lewis J.R. (2011) when designing usability questionnaires, is it painful to be positive ?. Proceedings of the Human Factors in Computer Systems Conference (CHI 2011), Vancouver, BC, Canada.
- Tullis, T.S., & Stetson, J.N. (2004). Comparison of questionnaires to evaluate the usability of websites. Proceedings of the UPA conference.