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Introduction
Charting multi-dimensional (multivariate) data on 2D paper or computer screen is a challenge. Several of Excel's standard chart types are often used to chart 3 - 4 variable situations even though these chart types are not effective from a data visualizations standpoint. Stacked/clustered bar charts, multiple series area charts are frequently used even though they are difficult for viewers to interpret.
Cleveland advocates the use of trellis like displays, Tufte advocates the use of small multiple charts. Advanced statistical and graphical packages allow users to prepare trellis, small multiple charts.
While not a default chart type, Excel users can develop trellis display/small-multiples like charts in Excel by using standard Excel XY charts, data transformation to shift data points to coordinates for appropriate panel and dummy axis series to label axes.
What is an appropriate name for the multi-plot charts in Excel? The term trellis display has been trademarked by Insightful Software (S-Plus). The term small - multiples has long been associated with Tufte, who has been very critical of Excel charting. I have coined the term "panel chart" to reflect the fact that the overall chart is composed of a series of panels that contain individual plots within a single Excel chart.
Excel Panel Chart Examples
The following example Excel panel charts show you what you can do with Excel, data transformation and dummy axis series. Click the link to go to the tutorial page to see how the panel chart was made and to download the demonstration workbook.
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