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Each of the 4 TECH Metrics are averaged into a Single Usability Metric (or SUM). The DXS number one receives is the mean of the four metrics provided: Task Time (or “Time to Hello World”), Error Rate, Completion Rate, and Happiness. To provide a better understanding of how this works, we can work with an example. In the below example, the DXS would be an average of the four metrics of 74, 85, 90, and 80. This results in a DXS score of 82.
Task Time Error Avoidance Completion Rate Happiness
74% 85% 90% 80%
Each of the metrics in the table are defined as below:
  • Time to Hello World (or Task Time) – What percentage of developers complete the task within the Target Time?
  • Error Rate – What percentage of developers report encountering errors during their task?
  • Completion Rate – What percentage of developers succeed at the task for the given timeframe?
  • Happiness – Average of responses to the Computer System Usability Questionnaire (CSUQ) developed by IBM (as compared to the CSUQ benchmark).
A perfect DX score of 100 would include 100% Error Avoidance, 100% Completion Rate, all participants completing the task within 30 minutes, and scoring “Strongly Agree” on all CSUQ criteria.

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