Measurable Activity is any properly defined activity is measurable. At a minimum, the number of cases coming into the activity, the time in the activity, the error rate, and multiple other factors can be measured. That an activity can be measured however, does not mean it should be measured. A measurable activity is one that should be measured. It may be a cost driver, a quality checkpoint, or something else. But care should be taken in identifying measurable activity because it is easy to measure the wrong things, and it is easy to over‐measure and create worthless reports.
Source: Guide to the Business Process Management Body of Knowledge – ABPMP BPM CBOK V3.0.
Also, read our complete BPM Guide online: The BPM Cookbook.