What is a choropleth map and what tools to use to create one

When displaying data, it is important to do so in a way that is as clear and as accurate as possible. This is particularly important when presenting data to an audience that may not be experts in that field. One of the most popular and effective ways of doing this is by using a choropleth map.

What is a Choropleth map?

Choropleth maps are some of the most commonly used types of visual aids today. They use color to display data as shaded points, lines, and areas. A common example is the use of choropleth maps to show census data. The data is displayed as a map of shaded areas, each area using a different color or shade to denote a data point. They are useful tools as data is often collect as enumerated units. Choropleth maps help show these units visually, therefore making the data easier to understand for the layperson.

Points to Remember When Making a Choropleth Map

Advantages and Disadvantages to Choropleth Maps

The big advantage of using choropleth maps is that they are able to express large amounts of collected data in a succinct, visual way. For example, population density is best expressed through choropleth maps. The combination of space and population density can easily be mapped onto a visual aid to help show how the data relates to the reality of the land type.

Some big advantages of using choropleth maps:

  • Statistics and data can be displayed quickly and easily
  • Choropleth maps can be scaled to suit any amount of data, so long as areas do not become too small.

There is a drawback to displaying data in this way, however. Due to pre-existing boundaries, it can limit its ability to represent data realistically. This is because it does not allow for detailed fluctuations in the statistics to be shown.

It is important to remember that all maps are just one version of the reality they represent. They are not objective. They are dependent on many decisions about what is shown when they are being drawn.

Color Theme

It is important to choose the most effective color progressions to use when making your choropleth map. Always consider the data you want to represent, and think about how best to display it visually, using color.

Sometimes, cartographers use single-hue themes. This means that one color is used for the entire data set. The different data points are shown through a fading from dark to light, often including black and white at both ends of the spectrum. Dark usually represents the largest number, while white represents the smallest.

Classes of Map

As mentioned earlier, choropleth maps often handle numeric data. This means that the data must be standardized as opposed to raw. They are sorted into two types: classed and unclassed.

  • Classed maps present data using a single color, but in a variety of shades from dark to light.
  • Unclassed choropleth maps use a gradient display of multiple colors to depict data. The major benefit of this type is that it can aid in displaying the data ranges more realistically, as it mitigates for variations in the data set.

When a Choropleth Map Should Be Utilized

The most common usage of choropleth maps is in visualizing population data. For example, employment rates and population densities.

They are extremely effective at showing the contrast between different pieces of data and making the impact more pronounced, especially for non-experts. If the data you are representing does not include regional patterns that would benefit from this type of visualization, then it may be worth considering an alternative.

The main use of choropleth maps is to show a more overall view of a collection of data — the bigger picture of what the data and research represent. They are not as good at showing detailed results, as they do not account for small variations in numeric data. Intervals between colors may not line up directly with those in your numeric data. By their very nature, they generalize.

We have linked two great examples of choropleth maps below to show how they can be used to great effect.

9 of the Best Tools to Make Choropleth Maps With

Creating your own choropleth map can be tricky at first. Luckily, there are many useful tools available that can make the process much simpler.

1)   MapSVG

choropleth Map created with MapSVG

MapSVG allows the user to display content as a vector, image, or Google Maps. It is a commonly used plugin to make choropleth maps with and includes options to use filters and searches as well.

You can convert your numbers to colors on the map. In this way you can show statistical information and visualize your data.

It actually does more than this. You can create objects with custom fields: people, locations, events, real estate properties, or anything else. Import large data sets from a CSV file. Use a built-in template and CSS editors to set up the look of your content on the front-end.

2)   amMaps

This is a great tool that lets you make choropleth maps quickly and easily. When an area’s value changes, it automatically changes your map and the associated gradients.

3)   AnyChart

This is another great online tool that helps you to create choropleth maps by assisting you with the coding process, which in turn will allow the user to embed the maps wherever they wish.

4)   Datamatic

This editor is built on the data visualizer d3.js. It allows anyone to make easy choropleth maps with the speed and simplicity of familiar software such as Excel.

5)   Datawrapper

Datawrapper helps you simply map your data onto choropleth maps. The resulting maps are responsive and dynamic.

6)   Infogram

This tool has a huge range of styles of choropleth maps for you to choose from. There are over 500 available! Each one is shareable over social media, presentations, and more.

7)   JSCharting

This software offers more functionality than others. If you want to not only create maps but edit and customize them, then JSCharting is a good choice.

8)   Kartograph

Another great choice if you need to create clear and simple visualizations of your data is Kartograph. Easy to use for novices.

9)   Polymaps

This JavaScript library is free to use and offers a wide range of interactive maps to choose from. It is guaranteed to display your data in a dynamic way.

The Benefits of Using a Choropleth Map Are Clear

There is a reason that choropleth maps are already so widely used. They display data in a visual way, that makes the meaning and consequences of that data clear for all to see — including non-experts.

It is important to remember the failings of these maps, however. By the very nature of their design, they cannot show nuanced differences in numeric data. They generalize results for an overview rather than an in-depth look at the results.

However, if this is kept under consideration, they can be utilized to great effect. As with everything, it is important to consider what exactly your data is, as well as what it is attempting to show. This will ultimately help you decide whether or not using a choropleth map is the right way to go.

If you enjoyed reading this article about the choropleth map, you should read these as well:

← Back to blog