Usability Metric for User Experience

The Usability Metric for User Experience (UMUX) is a standardised attitudinal survey, particularly useful for tracking the perceived ease of use and perceived usefulness of products when the physical space for survey questions is limited (such as inline forms on web sites and mobile applications).

From SUS to UMUX

UMUX was inspired by System Usability Scale questionnaires, after early trials at product teams in Intel revealed that a 10-question survey is too large to include in regular research.

Finding that answers to some individual questions in the SUS survey highly correlate to the final scores, and that the survey provides feedback both about ease of use and ease of learning how to use a product, Kraig Finstad created a four-question survey that is significantly simpler, while closely matched SUS results in research (with a correlation rate of “higher than 0.80”).

Finstad described UMUX, along with the results of the research at Intel, in a 2010 article for the Interacting With Computers Journal. Later research further simplified the survey, without losing too much on relevance or relatability.

UMUX survey

The UMUX survey consists of 4 statements, similarly to SUS interleaving positive and negative statements to reduce variability and biases. In a significant difference from SUS, the UMUX questionnaire requires the respondents to rate agreement with the statements on a 7-point Likert Scale (SUS used a scale of 1-5).

# Question Strongly Disagree Strongly Agree
1 [This system’s] capabilities meet my requirements 1 2 3 4 5 6 7
2 Using [this system] is a frustrating experience 1 2 3 4 5 6 7
3 [This system] is easy to use 1 2 3 4 5 6 7
4 I have to spend too much time correcting things with [this system] 1 2 3 4 5 6 7
The UMUX survey tracks the most relevant two positive and two negative statements from SUS.

The survey is scored similarly to SUS. Statements 1 and 3 are normalized by subtracting 1 from the value selected by the respondent, and statements 2 and 4 are normalized by subtracting the user-selected value from 7. That way, each statement is scored on the scale of 0 to 6. To make results comparable with SUS, the final score is calculated by adding the individual normalized row scores, dividing by 24 and multiplying by 100.

UMUX-LITE survey

In 2013, James R. Lewis, Brian S. Utesch and Deborah E. Maher, who were all then working for IBM, argued that efficiencies of UMUX of reducing 10 to 4 questions are not that significant, and that the questionnaire can be further simplified to keep only the positive statements. They published the results of their research in the paper UMUX-LITE: when there’s no time for the SUS, calling the reduced two-statement survey UMUX-LITE. According to the paper, the reliability of the new variant is between 0.82 and 0.83, with a significant correlation with SUS (0.81) and with the Net Promoter Score (0.73) rating methods.

# Question Strongly Disagree Strongly Agree
1 [This system’s] capabilities meet my requirements 1 2 3 4 5 6 7
2 [This system] is easy to use 1 2 3 4 5 6 7
The UMUX-LITE survey tracks only two positive statements from UMUX.

The Lite is scored differently than the original, to correct for a discrepancy between UMUX and SUS scores. First, because the questionnaire only contains positive statements, the normalized scores are always calculated by subtracting 1 from the values the users selected. Second, to keep the final score consistent with SUS, the final value is not scaled linearly, but divided by 12, multiplied by 65, and then added to 22.9.

UMUX-LITE = (Row1 + Row2 - 2) * (65/12) + 22.9

However, in 2020, Urška Lah, James R. Lewis and Boštjan Šumak suggested in the paper Perceived Usability and the Modified Technology Acceptance Model that a linear scale (divide by 12, multiply by 100) would be more appropriate.

In the book Quantifying User Experience, Jeff Sauro and James R. Lewis suggest that UMUX-LITE “appears to be an ultrashort reliable, valid, and sensitive metric that, after applying the regression adjustment, tracks closely with concurrently collected SUS scores”.

UX-Lite survey

In 2020, Lewis and Sauro published Simplifying the UMUX-Lite, modifying and simplifying the wording of the LITE variant, with research proving that there are no significant statistical differences in results. Their proposed variant sounds less technical and talks more about user needs than user requirements, and inverts the sequence of questions. Lewis and Sauro called this variant UX-Lite (User Experience—Lite Questionnaire).

# Question Strongly Disagree Strongly Agree
2 [Product name] is easy to use 1 2 3 4 5
1 [Product name] functionality meets my needs 1 2 3 4 5
he UX-Lite survey rephrases UMUX-LITE making it less technical and more relatable to user needs.

The scoring for UX-Lite is identical to the scoring for SUS, and it is scaled linearly. The key benefit of reverting back to a five-point scale is the ability to easily compare results with existing benchmarks developed with SUS tests.

Learn more about the Usability Metric for User Experience

Alternatives to the Usability Metric for User Experience