Crystal Basics: Charts and Graphs

Everyone wants you to draw them a picture, it seems. People want a graph or a chart, so they can clearly see trends and relationships at a glance. Crystal Reports has a powerful graphing and charting engine, and provides you with 36 different types of charting templates. Plus, you can create your own charting templates.

While the Chart Expert makes graphing and charting easy, there are some things you should know.

The four general categories (layouts) of graphs are:

1. Advanced. You plot X and Y values. You can specify summary fields, perform TopN/Sort analysis, and control information grouping in the display. You used advanced graphs with formulas, but you do not need to insert a group or summary field into your report to use one.
    
2. Group. This is likely the most commonly used form of graph. You use this where there is a group inserted into your report and you have a summary field (e.g., sum, average) based on that group. Such a graph can appear once, or it can appear on the group level with a separate graph for each group. You can use it to create a drill-down effect, where you start with a graph of the highest data level (e.g., gross sales) and then keep showing subsequently deeper levels of data (e.g., sales by region, sales by account, sales by product). A group graph, unlike an advanced graph, requires a group or summary field.
    
3. Cross-tab graphs. This is similar to a group graph, but you use a cross-tab for the data source, instead.
    
4. OLAP grid graphs. This is similar to a group graph, but you use OLAP grids for the data source, instead.

You can create graphs in the various formats (most of them in both 2D and 3D): bar, line, area, pie, doughnut,riser and surface, XY scatter, radar, bubble, and stock. As with Excel, you may need to change the sort order or XY fields for the graph to clearly convey the information.

New in Crystal Reports 8.5 is the Analyzer, which allows you to control the chart’s appearance and formatting without using a third-party editor.

In a training course, one of the students completed his Ph.D. in statistics on presentation of statistics in charts. He objected to the standard exercise using a pie chart. He insisted they were evil and should never be used. While not quite as passionate about the subject, we agree he raised some excellent points.

Pie charts show only ratios, and poorly at that. It is difficult for the human eye to compare slices if there are lots them and they aren’t adjacent. Pie charts suit only a small set of data values, and have major problems if there are any negative values.

The other point that was very important was to avoid the temptation to use lovely 3D effects on our charts. While this looks nice, it can obscure the numbers we are trying to display. The 3D effect often makes values look closer than they really are.

Also think about the sequence of your values in the chart. Select a sequence that best displays the data.

Some factors to consider for best readability:

• Point of the chart. Ask why this chart exists, and make decisions based on your answer.
   

• Information focus. What information does the user most need? Least need? Decide what's important and leave out everything else. Lasers are powerful because they focus. Do the same, so your charts are powerful.
   

• Color contrast. Because your information is focused, you don't need a large pallet of colors because there aren't many things to color. Aid the eye by using contrasting colors.
   

• Font size. Don't reduce the font as a way of cramming more onto the graphic. Instead, write less. Use short tags and labels, rather than long ones.
   

• Amount of information (lean toward "less is more"). The key points will get lost of there's too much information.
   

• Chart type. Use the chart type that best conveys your central message or best permits a clear portrayal of the data. Most people go straight to the pie chart, even though that's seldom the best chart type.