The purpose of a graph is to present information in a clear, visual way. These simple illustrations help readers understand the meaning behind your data so they can ultimately draw insights that lead to action. In many cases, data points in a table or a database are meaningless until someone fashions them into a graph.
Bar graphs and line graphs are the two most common graph varieties you’ll use to display your data. These are staples of data visualizations that work in almost all cases (unless you have extremely specific needs).
In this article, we’ll help you familiarize yourself with bar graphs and line graphs in order to use them appropriately. We’ll also show you how to turn your Gravity Forms data into both types using GFChart.Bar graphs and line graphs are staples of data visualizations. Click To Tweet
What is a Bar Graph?
A bar graph uses rectangular blocks of different heights. The height of the block corresponds with the value of whatever quantity is represented. There are two kinds of bar graphs: vertical bar graphs and horizontal bar graphs.
A vertical bar graph (sometimes called a column chart) should be used whenever you have nominal categories, like age groups, months, salary ranges, or other groups that make the most sense when viewed sequentially. The following example places sequential categories on the horizontal and values on the vertical. Undoubtedly, you’ve seen plenty of these.
The sequential categories of a vertical bar graph should always be displayed in their natural order. It would be confusing, for instance, if the months of the year were listed out of order.
A horizontal bar graph is best used when the categories are nominal (meaning there’s no clear order to them; they can be listed in any way), such as ice cream flavors, sales team members, revenue sources, etc. The values are represented on the horizontal axis. Here’s an example.
Don’t worry too much about that distinction. Choosing the right bar graph orientation will add clarity to your data visualization, but only a little. In most cases, either orientation will do.
When to Use a Bar Graph
The flexibility of bar graphs means they’re useful in countless situations as long as you can divide your data into neat categories so that each bar has a clear meaning.
For instance, if your bars are labeled with the months of the year, it would be inappropriate to divide one of those months into smaller groups (e.g. April, May, June 1-15, June 16-30, July, August…). Similarly, if you were showing the revenue of different companies, you wouldn’t give “Acme Inc” and “Acme Inc sales department” their own bars. That breaks the reader’s ability to grasp the distinctions between each category.
If you think the reader would also like to know the percentage relationship between categories on a bar graph, opt for a pie chart instead. A pie chart shows how each category relates to the whole. For instance, knowing the vote totals of each candidate in an election is helpful, but the percentage each candidate won of the electorate is more valuable.
Bar graphs should be scaled to zero. This means the axis with values should start at zero and extend at least as high as the biggest category. This is important because the area of each bar implies volume. Whatever you’re measuring is represented by the bar, so it’s appropriate to display the entire bar.
What is a Line Graph?
On a line graph, we plot individual points on the two axes and join them with straight lines. The vertical axis can represent any kind of value. The horizontal axis, however, should almost always represent time or some quantity that increases sequentially (like distance, age, stage of a project, etc.).
Line graphs are especially good at illustrating changes and trends. The lines between the individual points help us understand how those points change.
In the image above, for example, the red line shows that the percentage of U.S. households who earn less than $10,000/year has fallen over time. The decrease is too slight to see if we were looking at non-visualized data points in a table, but the line graph illuminates the trend.
Furthermore, line graphs are adept at showing numerous quantities over time by using multiple lines. This is great if you want to compare the change in one category versus the change in other categories.
When to Use a Line Graph
Line graphs are best used when you want to show changes over time. They are less versatile than bar graphs (because one axis has to be time), but their ability to show the direction of trends is unparalleled, especially when the changes are slight.
Since a line graph shows the changes in data points over time, it doesn’t represent volume. This means you don’t have to scale the graph to zero. If the lowest value on the vertical axis is 20, it’s fine to start the axis at 20 and extend it to the highest value. (Realistically, however, you would start the axis lower than 20 so there’s some whitespace, but you get the idea.)
Graphing in GFChart and Gravity Forms
Building your own bar graph or line graph from a Gravity Form is simple with GFChart. If you don’t have GFChart yet, grab yours today.
Before you get started, you’ll need to set up a Gravity Form and submit some entries. If you’re a Gravity Forms user, you may already have some existing forms with entries.
To create a graph for your form, click Chats/Calculations in your WordPress backend. This will take you to GFChart’s graph builder. Click Add New to get started.
Give your new chart a name. Use something you’ll remember to distinguish it from other forms. Next, select the Gravity Form from which it will pull data. Then click Create Chart/Calculation.
Now it’s time to build your graph!
- In the Design tab of the chart configuration editor, choose the Bar option, its orientation, and its legend position.
- On the Select Data tab, assign the X-axis (you categories) and any other features that suit your needs.
- On the Customiser tab, give the chart a title, size, and label.
- The Preview tab will (as you can probably guess) give you a preview of your chart. If you aren’t happy with its appearance, you can always navigate back to the other tabs to make tweaks until you’re happy with it.
Displaying your chart is just as easy. Simply grab the shortcode from the right side of the chart editor and paste it into any page or post using Gutenberg’s shortcode block.
Creating a line graph follows the same process except you’ll choose the Time option on the Design tab and choose Line for the Display Type.
Choosing the Right Graph
When you choose a type of graph to display your data, the best solution is the one that accurately conveys the information. Line graphs are best for plotting points over time. Bar graphs are best for comparing distinct categories.
That said, don’t bind yourself to hard rules. There are always exceptions. Your goal is to format your data in a manner that’s easily digestible for the reader without sacrificing accuracy or reliability. Sometimes that requires an unconventional approach, depending on the type of data you’re trying to display.
By now, you should understand bar graphs and line graphs, how they work, and how to set them up in GFChart. Use this guide to design clear visualizations that help you, your team, your customers, and your readers understand your data.