Which feature in Power BI allows users to display the spread of data around a central value?

The feature in Power BI that allows users to display the spread of data around a central value is error bars. Error bars are graphical representations that indicate the potential error or uncertainty associated with a data point. They can visually demonstrate how data points deviate from a central value, such as a mean or median.

By using error bars, users can easily identify the range of variability within a dataset. This is particularly useful in scientific and statistical analyses, where understanding the confidence intervals or variability around a measure can provide critical insights. They enhance the interpretability of visualizations by allowing viewers to gauge the precision of the represented data points.

The other options, while useful in certain contexts, do not specifically focus on displaying data variability. Reference lines indicate a standard value for comparison, data labels provide information about individual points, and trend lines show the general direction of data over time without emphasizing spread or variability around central measures.