Pitney Bowes MapXtreme - Manual (Page 278)

Chapter 14: Using Themes and Legends
RangedTheme
MapXtreme v7.1 285 Developer Guide
Types of Ranged Values
MapXtreme can create ranges automatically using five distribution methods:
• Equal count
• Equal ranges
• Standard Deviation
• Natural break
• Quantile
• Custom
Equal Count
Equal Count has the same number of records in each range. If you want to group 100 records into 4
ranges using Equal Count, MapXtreme computes the ranges so that approximately 25 records fall
into each range, depending on the rounding factor you set.
When using Equal Count (or any other range method), it’s important to watch out for any extreme
data values that might affect your thematic map (in statistics, these values are referred to as
outliers).
Equal Ranges
Equal Ranges divides records across ranges of equal size. For example, you have a field in your
table with data values ranging from 1 to 100. You want to create a thematic map with four equal size
ranges. MapX produces ranges 1–25, 26–50, 51–75, and 76–100. Keep in mind that MapXtreme
may create ranges with no data records, depending on the distribution of your data.
Standard Deviation
When you create ranges using Standard Deviation the middle range breaks at the mean of your
values, and the ranges above and below the middle range are one standard deviation above or
below the mean.
Natural Break
Natural Break is a way to show data that is not evenly distributed. It creates ranges according to an
algorithm that uses the average of each range to distribute the data more evenly across the ranges.
It distributes the values so that the average of each range is as close as possible to each of the
range values in that range. This ensures that the ranges are well-represented by their averages, and
that data values within each of the ranges are fairly close together.
Quantile
Quantile is a second way to show data that is not evenly distributed. Quantiling uses two variables
expressions. For example, use the Quantile distribution method to show the literacy rate as tied to
population.