Final answer:
The number of categories in a statistical map should be limited to ensure clear distinction between classes.
Step-by-step explanation:
In a statistical map, the number of categories should be limited so that classes can be distinguished. The optimal number of categories depends on the data and the purpose of the map. Generally, it is recommended to limit the number of categories to around 5-7 to ensure clear distinction between classes. This helps avoid excessive overlap or confusion in the map.
For example, if you are creating a statistical map to show population density, you might want to divide the data into categories such as 'Very Low', 'Low', 'Medium', 'High', and 'Very High'. This provides a clear representation of the different population density levels across the map.
Remember, the goal of a statistical map is to effectively communicate information, so the number of categories should be chosen with clarity in mind.