What is a Line Graph and when to use it?

The line graph is one of the most common types of data visualization. With this type of graph, it is possible to display one or more lines to represent different variables.

It is very useful and easy to understand, allowing, in its most common use case, to show the evolution or trend of a variable over time.

Read on to learn more about the topic, find out when to use it, and other important information. Follow along!

What is a line graph?

A line graph is a type of graph that is used to represent the evolution or trend of a variable over time. It is a visual representation that displays a series of data points connected by a straight line.

The horizontal axis of the line graph usually represents time (X-axis), while the vertical axis represents the variable in question (Y-axis). Each data point is represented by a point on the graph, and the points are connected by a line that shows the progression or variation of the variable over time.

Line graphs can also display multiple lines. In this case, two or more variables are represented on the same graph, each with a distinct line. This type of graph is useful when comparing the evolution of different variables over time, allowing for the visualization of possible correlations or trends between them. Each line can be identified by a different legend or color, making it easier to understand the data.

How does a line graph work?

Let’s give a practical example to illustrate how a line graph works. Think of a scenario where a company wants to analyze the performance of its stocks over time.

In this case, the horizontal axis of the graph would represent time, with data organized by days, weeks, or months, depending on the analysis needs. And the vertical axis would represent the stock price. Each point on the graph would be a closing price of the stock at a certain period (day, week, month), connected by a line representing the price evolution over time.

Analysis of the line graph could indicate an upward trend (ascending line), a downward trend (descending line), or stability (straight line) in the company’s stocks, allowing investors to make informed decisions based on historical data.

When to use a line chart?

A line chart should be used when you want to visualize the trend or evolution of a variable over time, allowing the reader to quickly identify patterns and trends in the data.

Line charts are often used in financial analysis to show the performance of investments over time, in market research to illustrate sales trends, in scientific studies to track the evolution of variables such as temperature, pressure, humidity, and in many other applications.

Line charts are easy to interpret and are an effective tool for data visualization. If you need to analyze data that changes over time or with another independent variable, a line chart can be a great option to present this data clearly and objectively.

What are best practices when developing a line chart?

When developing a line chart, it is important to follow some best practices to ensure that it is clear and easy to interpret. Here are some tips for developing an effective line chart:

Choose axis scales carefully

It is important to choose the appropriate scale for the vertical and horizontal axes so that the data is presented clearly and without distortions.

Use colors and legend appropriately

If you are representing multiple lines on a chart, it is important to use distinct colors and a clear legend to identify each line.

Use informative titles and labels

A clear and descriptive title can help the reader quickly understand what the chart is showing. Additionally, it is important to label the axes and lines appropriately to ensure that the data is easily understood.

Avoid overloading the chart

It is important to present the data in a clear and concise way, without overloading the chart with too much information or unnecessary details. For example, avoid showing too many lines on the chart as it may compromise readability.

Be consistent

When presenting the data, it is important to be consistent throughout the chart. Make sure that the units, scales, and intervals are the same throughout the chart.