Final answer:
Nina is likely examining clearance rates, which indicate the police's effectiveness in identifying suspects in reported crimes. High clearance rates denote effective case closures through suspect identification.
Step-by-step explanation:
Nina is likely examining clearance rates, which refer to the percentage of cases in which the police have identified a suspect, irrespective of whether a conviction has been secured. High rates of suspect identification show that the jurisdiction's police are effectively closing cases by identifying offenders. This does not necessarily reflect the overall crime rate, which includes both reported and unreported crimes, or dictate that the crimes are solved, but rather it is indicative of police efficiency in certain aspects of their investigation process.