Which is more useful, a legend or data labels?

The appropriateness of using a legend or data labels largely hinges on the specific context of the data being presented, which makes "it depends on the data being displayed" the most accurate choice.

In scenarios where a graph has multiple data series or categories, a legend is immensely helpful as it allows viewers to easily understand what each series represents without crowding the visual with excessive text. For example, in a line chart where multiple lines represent different metrics over time, the legend clarifies which color corresponds to which metric.

Conversely, data labels can be more effective in situations where specific values are important to convey directly. For example, in a bar chart showing sales figures for various products, adding data labels directly onto the bars can provide immediate clarity about performance figures, enhancing comprehension at a glance.

Choosing between legends and data labels is not a straightforward matter; it is essential to consider factors such as data complexity, the number of categories, viewer preferences, and the overall clarity of the visual representation. Thus, the decision on whether a legend or data labels are more useful must be tailored to the specific data and the message the presenter wishes to communicate.