Hello again Kieran,

I think I may have found a simpler solution. Because the metric I'm using is capturing the duration separate from the value field, I modified the script to set the value to current.assignment_group.name.

function createMetrice(value) {

  var gr = mi.getNewRecord();

  gr.value = current.assignment_group.name;
  gr.start = current.sys_updated_on;
  gr.end = gs.nowDateTime();
  gr.duration = gs.dateDiff(gr.start.getDisplayValue(), gr.end.getDisplayValue());
  gr.calculation_complete = true;
  gr.insert();

With this addition, I'm now able to filter the instances based on the value to exclude assignment groups I don't need to count the metric instance for...

I know it's not very elegant because to filter the report requires a perfect match of the assignment group name to but if I could get away with just one metric I'd prefer this method.

What do you think?

Kevin