Balancing KPIs helps prevent unintended behaviors and gaming. “First call resolution rate (%)” can be improved in ways that increase cost or reduce efficiency (e.g., agents spending excessive time on calls to ensure resolution). The most appropriate balancing KPI among the options is call duration , because it captures the efficiency trade-off: higher resolution is good, but not if it requires unreasonably long calls that reduce capacity and increase wait times. “Calls per hour” or “calls per staff” are also productivity indicators, but call duration is more directly linked to the behavior that can inflate first-call resolution—staying on the phone longer. “Improve call resolution” is an objective/initiative phrasing, not a KPI. A common measurement challenge is optimizing one metric at the expense of another; balancing creates a guardrail that keeps performance improvements sustainable. In practice, contact centers often balance first-call resolution with average handle time, customer satisfaction, and repeat contact rate to ensure resolution quality and efficiency. Proper KPI documentation should define call duration calculation (talk time vs wrap-up included), exclusions, and targets that reflect service complexity.