Charts and Graphs
Charts as evidence
A chart turns a table into a visual argument. Know how to insert a chart, open its data sheet, add or remove series and categories, switch rows and columns, and change the chart type. Understand chart elements: chart area, plot area, title, legend, axes, gridlines, data labels and data table. Match the chart to the message: column or bar for comparison, line for trend over time, pie for parts of one whole, scatter for correlation. Format axes with number formats and set the scale deliberately.
Traps
If categories appear as series, use Switch Row/Column. A pie chart with many slices or negative values is a poor choice, and a pie cannot show trends. The legend names series; data labels show exact values on marks. Deleting a chart element is not the same as hiding it. Charts pasted into a slide may be linked to the source workbook or embedded; editing data in the slide changes the embedded copy.
Worked example
Given a table with months down the first column and sales across the top row, select the whole table, then Insert > Chart > Column. If the months appear in the legend instead of on the horizontal axis, choose Chart Design > Switch Row/Column. Add a chart title that states the finding, not just “Sales.”