Data can be classed by type of offense, time of day of offense, and age of offenders. With some types of data it is useful to group classes together for easier interpretation. For example, if we are listing numbers of offenses by time of day, it would be helpful to combine two or more hours together to form an hour group or interval. Another statistical aid to the PM and his staff is the calculation of percentages. Data presented in percentage form give a clear picture of problem area locations.
Percentages are also helpful in presenting briefings and reports.
A percentage is the relationship of a part to a whole calculated on the basis of 100. This method may also be used to determine percentage of increase or decrease in troop strengths. The only difference is that an additional computation must be made to determine the actual increase or decrease involved. They act as a common denominator to make evaluation and comparison easier. A graph or chart provides the PM with a medium for presenting facts in a clear, understandable, logical, and interesting manner.