Why would data be normalized to use with a choropleth map?

When creating a choropleth map, it is essential to have consistent and comparable data to effectively communicate the information represented in the map. Normalization of data helps in converting raw values into a consistent level of data representation, which allows for fair comparisons across different geographic areas or categories.

For example, if one region has a population of 1 million and another has 100,000, simply using the population values would not provide a true representation of density or other attributes when displayed on the map. Normalization can involve adjusting these values based on area size (such as people per square kilometer) or another relevant metric. This way, the choropleth map accurately reflects the information without bias caused by disparities in scale or total quantity, ensuring that viewers can easily interpret and compare the mapped areas.

In contrast to this correct approach, altering the visual appeal of the map, reducing the number of classes, or removing outliers do not focus on creating consistent data representations that are crucial for accurately interpreting choropleth maps.