Weaknesses of the Uniform Crime Report?

UCR figures do not provide an annual per capita measure of crime frequency. Not all law enforcement agencies report crime to the FBI, and those that do may fail to report crime uniformly. The same kind of crime may vary in definition among jurisdictions. The UCR only reports arrests, not the actual amount of crime, meaning if someone is arrested for robbery, but possess burglary tools, a concealed weapon, and stolen property, all of these events are crimes, but robbery would be the only one reported on the UCR.