Bar Chart Visualization Guide

When to use a bar chart

A bar chart is a classic method for numerical comparisons. The Many Eyes bar chart can show one or more sets of variables.

How our bar chart works

Interaction: To see the exact value represented by a bar on the graph, move your mouse over it. If you are graphing more than one data series, use the clickable legend to pick which graph to see. If you want to see more than one series at once, use control-clicks on the legend.

Highlighting: To highlight a bar on the graph, just click it. It will be outlined in orange. To highlight more than one bar, use control-clicks. Your highlights will be saved with any comments you make, so you can easily refer to particular parts of the chart.

Data requirements

A bar chart takes a table where each column corresponds one data series. One special column corresponds to the x-axis labels. For example, in this table the "Year" column would be used for the x-axis labels, and the two other columns would define two data series to be graphed. In certain cases you may want the x-axis labels to be taken from the column headers (many data spreadsheets have one column per year, for example). When you configure the visualization, you'll have an option to flip rows and columns.

Expert notes

Bar charts are classic diagrams that usually give a good picture of the data. Their main problem is that when there are many bars, labeling becomes problematic. They also imply that the data is discrete; if your data is something that is plausibly continuously changing over time, for instance, you might consider a line graph instead.