When to Use a Bar Graph: The Only Guide You Will Need
Bar charts have been around for centuries, with credit for their invention going to Nicolas Oresme in the 14th Century. In spite of that long history, it was the invention of personal computers that made them mainstream.
Today, you see bar chart examples everywhere – in textbooks, newspapers, magazines, and PowerPoint slide decks. They’re popular but they don’t suit every type of data. Let’s look at when to use a bar graph for the best results.
Why You Should Use a Bar Graph
Bar graphs are one of the easiest types of charts to interpret. It’s easy to see the difference between the bars and they’re simple enough that anyone can understand the point they’re meant to get across.
One of the most effective uses of a bar graph is to show comparisons between categories of some sort. For example, a bar chart would work well for comparing sales figures for different regions since it’s easy to judge the difference by the height (or length) of the bar.
Bar charts are also good at showing frequency distributions across a set of data, especially larger datasets. It’s easy to scan the chart and see how many bars are the same or similar length.
Horizontal vs Vertical Bar Charts
You can lay out bar charts out vertically or horizontally. A vertical chart has the categories on the X-axis at the bottom of the chart and the values being charted on the Y-axis on the side. A horizontal chart flips the two so the categories are on the side.
A horizontal bar graph works better when the category labels are longer and wouldn’t fit along the bottom of the chart. They also work better for datasets with a large number of categories since it’s easier to scroll vertically to see the entire chart than it is to scroll horizontally.
Vertical bar charts, also known as column charts, work better for sets with negative values. People think of negative numbers as being “below” zero so having the bars go below the zero line is more intuitive.
There’s no hard-and-fast rule for choosing your chart direction. Use whichever layout is more intuitive for the type of data you’re charting. Adobe’s Spark service shows you how to make a bar graph with either layout.
Comparing a Bar Diagram with Other Types of Charts
Besides bar charts, there are two other types of graphs that are commonly used:
- Pie charts
- Line graphs
These types of charts are better for certain types of data. Pie charts are more effective than bar graphs if you want to compare percentages. It’s much easier to visualize a percentage relative to the other wedges in a circle than by looking at bars that are side-by-side.
Line graphs work best for seeing trends. Because a line connects the individual data points, you can identify how the data is trending. For example, is it increasing or decreasing, are their larger changes between certain points, and is there a pattern over time?
Examples of When to Use a Bar Graph
We already mentioned one example of when to use a bar graph, comparing sales figures across several regions. In this case, a vertical layout would work best. For example, if you have 4 regions – North, East, South, and West – those would go along the X-axis at the bottom and the sales figures would go on the vertical Y-axis.
A chart comparing time spent on different types of smartphone applications would work better with a horizontal layout. The categories could include things like playing games, social media, reading ebooks, and taking pictures, all of which are long enough labels to cause problems on the bottom axis.
Next time you want to add a graph to a document or presentation, think about the type of data and the point you want to get across to your audience. That will help you choose the best type of chart for your needs.
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