What are line charts
Line charts are one of the simplest graphs available and are common in many fields. They are most widely used to display data trends over a period of time and demonstrate the changes in the data values.
In digital marketing line charts are most commonly used to visualize data related to website traffic and conversion trends.
In this post I look into several line chart examples to show several different use cases.
Line Chart Use Cases
You can consider using a line chart if:
- You are showing how a certain data value has changed over time.
- You are comparing two or more categories and want to demonstrate how one took over the other or how the changes over time to these categories are related.
Line Chart Examples
- Simple line chart
Here is a line chart example showing a trend over time for Google searches related to Sushi.
Any data visualization tool can build this type of chart. The graph consists of the usual line chart components:
- The x axis – the time period
- The y axis – the data values
- The series – the line on the chart plot representing the category and its values’s trends over the time period
- Axis vs Data Labels on Line Charts
Depending on how you want to present your data, in a simple line chart you can remove the y axis and include data labels on the line instead:
Or you can only include several data labels to draw the attention on the important value changes:
- Double line chart
Line charts can also be used to show the changes in data values for more than one category (series). Line charts comparing the trend over time for two categories can be very useful to show how two categories may influence each other or simply show the bigger popularity of one of them:
- Multiple lines
While line charts are one of the basic charts in data visualization and are useful and common across many data sets, there are examples where line charts can be very ineffective. In the example below the line chart visualizes trends over time for 7 categories.
This makes the chart very cluttered and hard to read. It would be best to avoid potting multiple categories on a line chart. However if you have to work with multiple categories and trends there are design ideas that can help you plot a line chart and minimize the clutter.
In the next animated chart example I will show you an idea on how to plot a line chart if you are looking at multiple categories.
- Animated line chart
Flourish is one of my favourite data visualization tools. It is very easy to use and you can create impressive animated visuals. Line charts with multiple categories are a great candidate for animation. In this line chart example the lines change into grey color when the next line appears.
This is a nice way to highlight the category on a line chart that is most important and is the subject of analysis. With all other categories in grey the clutter is minimized.
- Line chart with annotations
Line charts have a lot of white space and since they show trends over time where anomalies can appear, annotations can be used to explain unusual increases and decreases.
The chart below shows the Google searches trend for flowers over several years. In this trend we can clearly see an uptick in searches on Valentine’s Day and Mother’s Day each year:
Line charts are one of the most effective charts when designed well:
- Use them to show trends over time
- Remove guidelines will reduce clutter
- Use an y axis or data labels, but not the two together
- Avoid plotting a line chart with multiple categories