Data Maps

Data Maps

In the world of data visualization, maps are not just tools; they are storytellers that transform complex datasets into compelling narratives. Among the various types of maps, choropleth maps, symbol maps, and locator maps each have unique characteristics and applications. Knowing when and how to use these maps can significantly enhance the clarity and impact of your data presentations. Hereโ€™s a casual dive into how these map types can be your best friends in visual storytelling.

For this blog I used three different datasets to tell three different stories; US airport delays in 2023, EV shares by country in 2023, and EV Drive Distances from Kulpsville. Additionally, I used the Datawrapper tool to visualize each of the datasets. Let’s look a little closer.

Choropleth Maps

First up is the choropleth map. These are the go-to for thematic mapping. They use color gradients to represent data values across predefined regions, such as states or countries. This makes them perfect for displaying data like voting results or unemployment rates. The key is to use these maps for data that is aggregated over geographic areas (Monmonier, 1991). However, beware of their limitations: larger regions can dominate the visual field, skewing perception. To counter this, use rates or per capita figures instead of absolute numbers (Datawrapper, 2021). As I learned with Datawrapper, itโ€™s crucial to know the story you want to tell and ensure your dataset is clean before selecting this map type.

For this story, I wanted to answer the question Which Airport in 2023 had the most weather delays? Before I could start for any of the maps, the process was the same; clean the data. That is, remove duplicates, unnecessary columns and/or rows that didn’t help tell the story. This dataset was challenging because there were over 10,000 rows of data just for the year 2023. The data was broken down by month, airport, airport name, and so on. Additionally, I had over 304 rows which were not recognized by Datawrapper. This meant going back into the dataset and filtering until I identified those 304 rows. It turns out it was airports outside the contiguous 48 states. Once this was fixed I was able to produce the Choropleth map below.

Symbol Maps

Symbol maps, or proportional symbol maps, are all about pinpoint precision. They use symbols of varying sizes to represent data values at specific locations, making them ideal for showing quantitative data like city populations or earthquake magnitudes. Unlike choropleth maps, symbol maps can display two variables at onceโ€”size and colorโ€”offering a richer data story (Cairo, 2016). These maps shine when your data is tied to specific points rather than areas, helping to highlight patterns or outliers with ease (Datawrapper, 2021). Remember, refining the data until your story is clear but not misinterpreted is key.

Next up was my dataset to help show which country had the largest percentage of EV shares across the world. This dataset was challenging too. There were two factors adding to the challenge. The first issue I ran into, after cleaning the data was that Datawrapper threw errors. Datawrapper couldn't use the percentage of new electric cars raw data because some were in decimal value and other values were whole numbers. For example, Chile and South Africa were in decimal value, the rest of the countries were whole numbers. This caused countries like Norway, whose value was 93 to be 9300%. Once I converted the whole numbers to decimals the data provided more accurate percentages in Datawrapper. Another cleanup I had to do was to obtain and input latitudes and longitudes for each of the countries for more accuracy. The outcome of this map can be seen below.


Locator Maps

Locator maps are your navigational aids. They provide context by showing the location of something within a broader geographical setting. These maps are typically static and serve as a reference point, helping viewers understand where an event occurred or where a specific place is located. They are often used alongside other map types to give context, such as placing a city within a country (Monmonier, 1991). When the goal is orientation rather than data complexity, locator maps are your best bet.

My locator map in Datawrapper used a dataset that combined two pieces of data merged into one. From there I went to https://www.511pa.com/#:Alerts and manually looked up distances from my starting point. Using each of the reported EV range at 70mph I looked up the distances and randomly plugged them into the end location field on my dataset. I thought it would be fun to see how far each of the reported EV's could get from the start location in Kulpsville, PA. In Datawrapper I also included the car details (year, make & model), tire size, and distance in miles inside the tooltip for each locator. This allows the audience to hover over and see the information so there is a reference point.


Conclusion

Choosing the right map type is crucial for effective data storytelling. Choropleth maps are best for regional data, symbol maps excel in representing data at specific locations, and locator maps provide essential geographical context. By understanding the strengths and limitations of each map type, you can craft visual stories that are both informative and engaging. And remember, with tools like Datawrapper, the process becomes all the more intuitive and rewarding.

Additionally, there are a number of tools for data visualization, but especially data mapping. For this blog I used Datawrapper. However, for future projects I plan to explore ARCGIS with my student plan for $100 annually. I will also plan to see about how to use Flourish as it offers more interactivity for my audience.

Resources

Monmonier, M. (1991). *How to Lie with Maps*. University of Chicago Press.

Cairo, A. (2016). *The Truthful Art: Data, Charts, and Maps for Communication*. New Riders.

Datawrapper. (2021). *How to show symbols on choropleth maps*. Retrieved from https://academy.datawrapper.de/article/334-how-to-show-symbols-on-choropleth-maps

Datawrapper. (2023). *From news media to Datawrapper: Six things I've learned in my first year*. Retrieved from https://blog.datawrapper.de/media-to-datawrapper-first-year/

Datawrapper Academy. (n.d.). *A collection of Datawrapper pro tips*. Retrieved from https://academy.datawrapper.de/article/256-a-collection-of-datawrapper-pro-tips

Can I unplug and walk away?

Can I unplug and walk away?

Data Detox Visualization – Legend
Oops! Photo Evidence almost ending the detox early
Data Detox Visualization – 5-Day Results
Look over hereโ€ฆHa! Fooled you.

Look over hereโ€ฆHa! Fooled you.

A magician doing a card trick
Adaptation of Nir Eyal’s Hooked model illustrated by Tony DeRose
A magician taking a final bow.