My statement was a general one about the claims of crime being down. How can you claim crime is down in New York, for example, if districts aren't reporting?
And yes, in certain aspects conclusions can be drawn with limited data. For example, if you only have 66% of a cohort involving a contagious disease and of that 90% died, it is reasonable to draw a confident conclusion. However, in this case a lack of data cannot cause crime rates/incidents to improve. Full data would make those statistics worse with near certainty