With groups of bars, a space shouldseparate the groups, but no space is necessary
between the bars of a group. The space between the groups of bars should be about the width of one bar or less.
· Data values should not be written either within the bar or outside it. If exact values are important, the data should be presented as a table. If bars are labeled with values, don’t use tick marks or grid lines.
· Don’t use tick marks on the X axis.
· Use the same fill color for all bars in single data set.
· Use different fill colors for positive and negative values.
· For single bars, center labels below each bar.
· For groups of bars, individual bars can be labeled. Group labels can be centered below the individual bar labels for vertical bar charts or placed to the left of the individual bar labels for horizontal bar charts. The groups can be labeled, and the bars can be distinguished by shading or patterns. Lettering in individual column labels should be smaller than lettering in the group labels.
· The longest bar (or its error bar) should reach nearly to the end of the chart. Figs. 26 and 27 illustrate the above points. They show basically the same information, but Fig. 27 is easier to read. Cluster or Segmented Bar Charts
· Use five or fewer segments per bar or bars per cluster.
· Use darkest or densest fills for segments at baseline (or left side) and lighter fills as segments rise up the bar (or move to the right).
· Display values over, next to, or in-