Dozens of incidents at the same address will look like only one symbol if they are stacked one upon another. Even the size of the symbol can cause some visual distortion. For these reasons, LPD's crime data is best viewed at a scale of no less than a typical city block. Complicating matters, for a variety of reasons not all crimes can be geocoded. Sometimes the exact location of a crime is unknown.
Human errors can happen at several steps in the process.
For example, an officer reverses two digits in an address, or a clerk inadvertently adds an extra zero during computer entry. Huge data files describing street segments, although highly accurate, also have their own errors and glitches. The computer software cannot recognize certain addresses that actually exist in the real world but are not present in the street database. The percentage of all events in a file that the software is able to geocode is often referred to as the hit rate . Even when a crime is geocoded, however, it can still be incorrectly placed on the map.