In many ways, though, definition of such skills is quite unnecessary for an ysis of policing. It is really most unlikely that the average police officer will ever in his career perform or even witness those detective skills that he has enjoyed in countless TV productions. The reason for this is simply that the vast majority of crimes are usually either very likely to be solved by routine investigation or they are very unlikely to be solved at all. Fortunately, the clear-up rate for serious crimes tends to be very high. Zander (1979) has shown why. In his study of old bailey cases, the identity of the defendant(被告) seems to have been reasonably clear in 87% of cases. Morgan (1980 and ongoing) has shown that well over 92% of crimes known to the police are discovered by the public who provide the majority of decisive information. In Morgan’’s study, crimes that were "solved" contained in their crime files over twice the amount of qualitative information as crimes that were not "solved". The various bits of information in the crime files were each rated by experienced police investigators on a Likert scale of value in terms of probability of detection, "solving" of the crime. In this, where information was. provided by the public during a police interview, the information was believed to the police "since it was felt that in an interview genuine police skills are involved in the collection of information." Evidently this method can be justified thus, but will necessarily overestimate the police role. Nevertheless, in this ysis of crime files it was shown that in cases where crimes were solved, the public still provided nearly twice the amount of information as the police. It can be learned from this passage that______.