About Chart Types

Keynote can create eight different types of charts , as shown in Table 8.1 . Each type of chart is useful for displaying a particular kind of data.

Table 8.1. Chart Types

I CON	C HART TYPE	D ESCRIPTION
	Column Chart	Column charts show unique values. They are useful when comparing values, such as sales, over different time periods.
	Stacked Column Chart	Stacked column charts, like area charts, display both individual values and the sum of several values for a given item.
	Bar Chart	Bar charts, like column charts, show individual items and their relationship to one another.
	Stacked Bar Chart	This variation of the bar chart is similar to the stacked column chart.
	Line Chart	Line charts show data trends over time or other intervals. They are useful for showing variations in values, such as stock prices.
	Area Chart	Area charts show the magnitude of change over time.
	Stacked Area Chart	Stacked area charts show the magnitude of change over time, and they display both individual values and the sum of all values in the chart.
	Pie Chart	Pie charts show proportional relationships between several values and a whole, often expressed as percentages.

It's not always easy to decide on which kind of chart to use. Sometimes the data that you're trying to present will practically beg for a particular chart type; for example, when you're trying to show values as percentages that add up to 100%, a pie chart is almost always the right approach. But in other instances, several chart types might fit your data and do a good job of presenting it. Here are a few tips to help you choose the right chart for the job.

• Evaluate the data that you are trying to present, particularly the aspect of the data that you want to highlight. Data where the totals are more important than the individual values are good candidates for area charts, stacked bar charts, and stacked column charts.

• If you have many data series to present, use a chart type like bar or column, which shows many data points well.

• Choose the chart type that produces the simplest chart for your data. If necessary, switch between the different types in Keynote to see the visual effect of each type on the data. Because your viewers don't have control of how long your slide is on screen, it will help if you give them charts they can grasp quickly.

• Pie charts shouldn't be used to represent data with more than 5 to 8 data series. Each series will appear as a slice of the pie, and too-small pieces will not have good visual impact.

Chart anatomy

Before you begin creating charts, you'll need to know a little about the terminology Keynote uses to refer to the different parts of a chart, and the different tools that Keynote gives you to manipulate charts. The column chart in Figure 8.1 labels the main parts that appear on a slide. Keynote provides the Chart Data Editor, which is a spreadsheet-like window where you enter the information that makes up the chart ( Figure 8.2 ), and the Chart Inspector, which gives you many controls that allow you to customize the chart ( Figure 8.3 ).

Figure 8.1. The parts of a column chart.

Figure 8.2. The Chart Data Editor resembles a spreadsheet, but it doesn't do any calculations.

Figure 8.3. The Chart Inspector gives you the controls you'll use to customize your charts.

The data for the chart appears in the chart area , which contains the bars, columns , lines, etc. All chart types (except for pie charts) have two axes, the horizontal X-axis and the vertical Y-axis . One of these will be the value axis , which is where you read the values you are charting. For example, in Figure 8.1, the value axis is the Y-axis. In column charts, area charts, and line charts, the Y-axis is the value axis. For bar charts, the X-axis is the value axis. Pie charts don't have a value axis.

Charts show the relationship between two types of data (for example, financial performance over a time period such as months or years ). These two data types are called the data series and data sets . In Figure 8.2, each row in the Chart Data Editor represents a data series, and each column represents a data set. The legend is the label or labels on the chart that explain what the different data series represent.