IsoMetrics is a tool that operationalizes the design principles of ISO 9241 supporting summative and formative evaluation of software systems. It has two versions, one short and another longer. The short one measures the summative evaluation of software, whereas the longer is suited for formative evaluations.

IsoMetrics assesses the usability of software products. It includes 78 items operationalizing the 7 design principles of ISO 9241 Part 1 on a five-point Likert scale. The IsoMetrics design provides information that can be used within iterative software development. It identifies and remedies any shortcomings, with the aim of enhancing its user-friendliness.

Overall it measures:

• Scores of the usability dimension to measure the progress of development.
• Concrete information about malfunctions and their user-perceived attributes.
• Mean weight of any user-perceived attribute, given a class of system malfunctions.

Covers USABILITY CRITERIA.

What makes IsoMetrics such a good tool?

The summative version of IsoMetrics shows high reliability of its sub-scales and gathered valid information about differences in usability comparing different software systems. The formative version of IsoMetrics is a powerful tool, because of its ability to pinpoint weaknesses within the software.

The 7 areas measure the users' overall agreement or disagreement with the user-friendliness of the software, as well as the factors that make up that facet.

Pros

• Categorize and prioritize weak points, which subsequently can be used as basic input to usability reviews
• 7 scores of the usability dimension to measure the progress of development.
• Concrete information about malfunctions and their user-perceived attributes.
• Mean weight of any user-perceived attribute given a class of system malfunctions.
• Provide data for multi-level validation procedures

Cons

• For uncommon prototypes, the validation study may result in insufficient validity of the instrument.
• The sum-scores of the sub-scales may not correlate with the problem count. Resulting in a mismatching between the usability problems and the questionnaire results.
• This method may try to make usability experts out of the users. IsoMetrics includes 78 checkpoints, 76% of which the users find difficult to answer.
• A user has to remember all the problems he had encountered and to correctly map them to questionnaire items seems impossible, especially if the user is asked to do so after testing which can take several minutes.

The questionnaire is composed of 37 questions on suitability for the task, suitability for the learning, conformity with user expectations, and effectiveness.

The unique usability checkpoints from IsoMetrics are Error tolerance, Operation speed, and Individualization.

• Suitability for the task

• Suitable for learning

• Error tolerance

• Self-descriptiveness

• Suitable for the task

• Controllability

• Conformity with user expectations