How is a trend line useful in data visualization?

A trend line is useful in data visualization because it represents the general direction of data points over time or across another variable. By plotting the trend line on a graph, it allows viewers to easily identify patterns, whether the data is increasing, decreasing, or remaining stable. This is particularly helpful in time series analysis, where observing how values change over intervals can inform decisions and strategies. Additionally, a trend line simplifies the complexity of the data, providing a clear visual representation of what is happening generally, even when the individual data points might fluctuate significantly around it.

Understanding the overall trend can be more insightful than focusing on each individual data point, as it helps stakeholders forecast future performance or make data-driven decisions based on observed behaviors.