Data displayed in a chart rather than a table are easier to understand and trends or patterns are easier to identify. Four basic data types that are easily charted are changes over time, percentages of a whole, comparisons, and relations between variables. Displays discussed are simple and double-scale curves; scatter and line plots; column, bar, and step charts; pie charts; patch maps; and combinations of these. Before making a chart develop a focus sentence, one that summarizes what is to be shown, and select a type of chart which illustrates that focus. Present only key points; extras detract from the message.