Operation Manual

Mapping
Mapping concepts
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302 Crystal Reports User’s Guide
interval may or may not be equal, depending on the individual regions
and their summary values.
• Natural break
This option assigns intervals using an algorithm that attempts to minimize
the difference between the summary values and the average of the
summary values for each interval.
• Standard deviation
This option assigns intervals in such a way that the middle interval breaks
at the mean (or average) of the data values, and the intervals above and
below the middle range are one standard deviation above or below the
mean. Standard deviation is the square root of the variance. It projects
how various values in a set of values deviate from the mean for that set.
Dot Density
A Dot Density map displays a dot for each occurrence of a specified item. For
example, you might create a United States map that shows one dot for each
shipbuilder in the nation. In states like Tennessee, there would be no dots.
However, in some coastal states, such as South Carolina, you might be able
to count the dots on the map, since their dispersal would be fairly wide.
The purpose of a Dot Density map is to provide an overall impression of the
distribution of the specified item. A Dot Density map is much like a nighttime
satellite photo of the United States, where you can see the lights of all the
cities. Such a map is not a very accurate means of communicating
information (particularly if you have a large number of items), but it is a good
way to give an overview of the distribution.
Graduated
A Graduated map is much like a Ranged map; it shows one symbol per
instance of a specified item. This symbol is a circle by default, but you can
choose a different symbol if you prefer. Each symbol is proportional in size to
the value of the item it represents (within a range of three sizes).
A Graduated map communicates the same information as the Ranged map,
but you would usually create a Ranged map for a case in which the
geographic areas have distinct geographic boundaries (as in the case of
Regions), while you would use a Graduated map for displaying data that is
linked to points rather than precise areas (as in the case of Cities).
For example, a map of an individual region could use graduated circles to
represent the sales for each office. The size of each circle would be
proportional to the sales (or to the sales range) of the office it represents. On
this map, an office with a sales figure of $70,000 might have a large circle,