About Ranged Maps - MapInfo_Pro - 2023

When you create a ranged thematic map, MapInfo Pro groups all records into ranges and assigns each record's object the color, symbol, or line for its corresponding range. For example, if you wanted to visualize the population of the world by growth rate, you would shade countries according to their reported growth rate amounts.

With the Ranged map feature, MapInfo Pro groups the growth rate amounts into ranges. For example, in the next table, all countries that had growth rates between zero and one percent are grouped into one range. Countries that had growth rates between one and 2.2 are grouped in a separate range. Countries that have rates between 2.2 and 3.1 are in a third range, and those countries reporting greater than 3.1 are in a fourth range.

Figure: Ranged Map

All records are assigned to a range and then assigned a color based on that range. For example, the countries with the higher growth rates are shaded in red. The other ranges are shaded in lighter shades of red to light green and finally darker green. When you display the map, the colors make it readily apparent which locations have the highest growth rate in relation to their neighbors.

Ranges are also useful when the size of the region is not directly related to the magnitude of the data values. In our population density example in this section, we see that countries that are small in size can be very densely populated, and countries that are large in size may not be densely populated. Differences like these are more readily apparent when the regions are shaded in this manner.

Types of Ranged Values

MapInfo Pro can create ranges automatically using five methods: Equal Count, Equal Ranges, Natural Break (Standard Deviation), Quantile, and Custom. To set ranges manually, use Custom.

Equal Count has the same number of records in each range. If you want MapInfo Pro to group 100 records into 4 ranges using Equal Count, MapInfo Pro 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 is important to watch out for any extreme data values that might affect your thematic map (in statistics, these values are referred to as outliers). For example, if you tell MapInfo Pro to shade according to Equal Count with this database:

Ben and Miguel are grouped in the same range (since they have the two lowest values). This may not produce the results you want since the value for Ben is so much lower than any of the other values.

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. MapInfo Pro produces ranges 1-25, 25-50, 50-75, and 75-100. (Since ranges use "=>" and "<=", they need to overlap.)

Keep in mind that MapInfo Pro may create ranges with no data records, depending on the distribution of your data. For example, if you tell MapInfo Pro to shade the following database according to Equal Ranges:

MapInfo Pro creates four ranges (1-25, 25-50, 50-75, and 75-100). Notice, however, that only two of those ranges (1-25 and 75-100) actually contain records.

Natural Break and Quantile are two ways to show data that is not evenly distributed.

Natural Break 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. MapInfo Pro bases its Natural Break algorithm on the procedure described by Jenks and Caspall in their article "Error on Choroplethic Maps: Definition, Measurement, Reduction" from the Annals of American Geographers, June, 1971.

Quantiling enables you to build ranges that determine the distribution of a thematic variable across a segment of your data. For example, you can quantile state population by urban population to illustrate how urban population is distributed across the United States. Your map legend will not indicate that you have used Quantile to build your ranges. You can customize the map legend so that it shows which field you used to quantile the table.

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. You can also define your own ranges using Custom.