What is the purpose of using error bars in a graph?

Using error bars in a graph serves to indicate the variability of the data. They provide visual representations of the uncertainty or variability associated with the data points being displayed. By showing how much the data might vary, error bars help to communicate the reliability of the measurements and the potential range of values, allowing viewers to assess the precision of the data more effectively.

Error bars can present information regarding standard deviation, standard error, or confidence intervals, giving critical insight into the consistency of the data collected. This helps to inform interpretations and comparisons made within the data set, highlighting the degree of variation that exists around an average value. By understanding the variability, practitioners can make more informed decisions based on the data presented.

Other options do not fully encompass the primary function of error bars. They don't directly track changes over time or specifically highlight extreme values. Instead, error bars focus on providing context regarding the variability inherent in the data being represented.