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are the global scores of the WAMMI and SUS questionnaires comparable? Does a website with a WAMMI score of 95 have a better usability than a website with a SUS score of 85? If they aren't directly comparable is there a known correlation or factor someone could apply to make the two comparable?

The last couple of hours I read a lot about these two questionnaires but couldn't find a resource stating the comparability either way, but maybe that's the entire point of having two score ranging between 0 and 100 even tough one incorporates more than the other.

thanks

Edit: WAMMI: http://www.wammi.com/whatis.html

SUS: http://www.usability.gov/how-to-and-tools/methods/system-usability-scale.html

After posting it I also found this sentence, I guess this answers the question, but maybe someone can confirm it.

...and SUS correlated very highly with simple average WAMMI scores (r = .948)

Source: http://uxpajournal.org/wp-content/uploads/pdf/JUS_Brooke_February_2013.pdf

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    Even a very high correlation doesn't mean the scores are directly comparable. In one system, an average score could be 50 with a few sites reaching 100. In the other, an average score could be 20 with only a few sites reaching 50. The correlation just means that the highest scorers on one system are also the highest scorers on the other (in general, that relative rankings are the same).
    – octern
    Mar 13, 2016 at 7:25
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    I'd like to recommend this article ncbi.nlm.nih.gov/pmc/articles/PMC4851667/#Sec2, it's about the comparison between standardized usability questionaries. good luck!
    – moises stevend meza rodriguez
    Feb 26, 2019 at 19:22

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As with any metrics or scores for the online/digital space, you have to fully understand exactly what you are comparing to make sure that you are making meaningful comparisons.

This why you normally wouldn't try to compare between two different types of rating systems, because they are designed for different purposes. Also, it is only meaningful to compare between the score ratings for that particular type of website rather than looking at general/overall scores.

I think the better thing to do would be to look at average SUS or WAMMI score breakdown for specific aspects of usability for the comparison that you are trying to make, and look at the correlation between those measures rather than the two rating systems overall.

In the end, I suppose it depends on the purpose of your questions, but I think the best answer for you will be to apply both measures to the website that you want to evaluate and see if there is a good match between the two or not.

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Generally speaking no, they are not. The global UX described by the SUS may vary from the general UX described by the WAMMI. So you are basically trying to compare different things that have a similar 0-100 scale.

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