You can create your own, fully customised metrics in ScaleXP's Metric Library, ready to be selected and reused throughout the system.
To add a new metric go to Settings (top bar, right side) > Metric Library (left sidebar) > Search for a relevant metric.
If what you're looking for doesn't exist, click Create new metric.
Note that the “Create new metric” button only appears after you have searched for a metric.
For an overview on the metric library see What is the ScaleXP Metric Library?