Write the denominator
For each measure, define the population, exclusions, time window, source fields, and owner. “Response time” can mean several different things unless the start and stop events are named.
Separate measures from goals
A metric describes observed work; a target is an owner decision. Do not turn a convenient number into a performance conclusion without checking quality and case mix.
Version the definition
Record changes to formulas, source systems, and periods so a later report can be understood. Reconcile a sample manually when the measure is first introduced or materially changed.