Data Visualization: Using Less-Common Charts
When you're trying to find visually appealing charts to display your data, it's important to keep in mind that the ultimate goal of any data visualization is to take a huge data set and display intelligence data in the form of charts, text, and other visual elements that are easy for the user to digest.
Here are three common chart types that lure beginners with their appeal but provide little to no value to readers, who are often confused by them:
Radar charts: Also known as spider or star charts because of their appearance, radar charts are designed to plot the values of different categories along a separate axis that starts from the center and ends in the outer ring, as shown in the following figure.
Although this cobweb of a chart definitely adds some appeal to your Big Data visualization, most users have no idea how to read the data. They get confused trying to decipher it without some accompanying text. It's advisable to stick a bar or column chart instead.
Candlestick charts: Candlestick charts were invented for the stock market and are used to describe the price movements of derivatives, security, or currency over time. Stock-market data is the only type of data for which this chart type should be used. Understanding when a candlestick is high or low isn't a concept that most readers are familiar with, so this type of chart will only serve to confuse them.
The figure below shows a candlestick chart displaying stock-related data.
Waterfall charts: These charts display the effect of positive and negative changes on a specific value over time. Waterfall charts are nicknamed "flying bricks" because they appear to be flying in midair.
The following figure shows a typical waterfall chart displaying financial profit/loss data. Colors on the bars indicate a negative or positive change in value, so you can easily see the $100,000 plunge that the company's profit took (from $420,000 to $320,000) and all the contribution costs in between.
While you should avoid using radar and candlestick charts, waterfall charts can be used once you've mastered more simple charts, such as bar charts, pie charts, and line charts. Waterfall charts aren't all bad, and their meaning isn't difficult for users to discern. When you do decide to use these charts, you should put some text at the bottom to help readers who are encountering this type of chart for the first time.
Focus on the message you're trying to convey. Charts were made for data; data wasn't made for charts. The message of your data should always dictate the charts you use. If you choose a chart based on its appearance first and then try to fit in data, you almost always confuse users, which lowers user adoption.