## Radar charts

Radar charts are listed in the Other Charts category. You may not be familiar with this type of chart. A radar chart is a specialized chart that has a separate axis for each category, and the axes extend outward from the center of the chart. The value of each data point is plotted on the corresponding axis.

There are three radar subtypes: the standard radar chart; a radar chart with data markers indicating each point; and a filled radar, where each series appears as a filled shape, somewhat like an area chart. No matter what subtype you use, choosing data for a radar chart isn't easy.

## Surface charts

Surface charts display two or more data series on a surface. Surface charts are listed in the Other Charts category. It’s important to understand that a surface chart does not plot 3-D data points. The series axis for a surface chart, as with all other 3-D charts, is a category axis—not a value axis. In other words, if you have data that is represented by x, y, and zcoordinates, it can’t be plotted accurately on a surface chart unless the x and y values are equally spaced.

A surface chart shows a 3-D surface that looks a little like a topographic map, complete with hills and valleys. Surface charts are different from most other charts in that they show the relationship of three values. Two category axes (X and Y) determine a data point's position. The value determines the height of the data point (technically known as the Z-axis). All the points are linked to create a surface.

Surface charts are neat to look at, but ordinary people almost never create them as they're definitely overkill for tracking your weekly workout sessions. For one thing, to make a good surface chart, you need a lot of data. (The more points you have, the smoother the surface becomes.) Your data points also need to have a clear relationship with both the X and Y axes (or the surface you create is just a meaningless jumble). Usually, rocket-scientist types use surface charts for highly abstract mathematical and statistical applications.

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