Open map List

Class Breaks

Class breaks in cartography refer to the threshold values used to group data into different categories for thematic mapping, especially in choropleth maps. These breaks define how continuous data is divided into discrete color or symbol categories, influencing the interpretation of spatial patterns.

Basic

Introduction

Key Aspects of Class Breaks:

  • Used in Thematic Mapping – Applied in choropleth maps, graduated symbol maps, and heat maps to classify data.
  • Affects Data Visualization – The choice of class breaks impacts how trends and patterns appear.
  • Different Classification Methods – Various statistical techniques are used to determine breakpoints.

Explanation

Common Methods for Defining Class Breaks:

  1. Equal Interval:

    • Divides the data range into equal-sized segments.
    • Best for uniformly distributed data (e.g., temperature ranges).
    • Example: Income groups split into $0–10K, $10K–20K, etc.
       

  2. Quantile (Equal Count):

    • Each class contains roughly the same number of observations.
    • Works well when data is evenly distributed across categories.
    • Example: Population density divided into four groups, each with 25% of the data points.
       

  3. Natural Breaks (Jenks):

    • Identifies clusters and gaps in data distribution to create meaningful groups.
    • Ideal for data with uneven distributions (e.g., land values, crime rates).
       

  4. Standard Deviation:

    • Classes are based on how much values deviate from the mean.
    • Used in statistical and economic analysis.
       

  5. Manual (Custom Breaks):

    • The cartographer sets specific breakpoints based on domain knowledge.
    • Useful when data-driven classification is not appropriate.

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