A major function of moderns spreadsheets is to provide a quick and easy way to plot numerical data in graphical charts of various kinds. The use of graphs provides users a way to explore data to discover relationships and trends in the data values. Graphs also provide an effective way to present data so as to demonstrate relationships in the data and summarize large amounts of data in an effective image. In Gnumeric, both of these can be done easily and efficiently. Information on the creation of graphical displays of data is presented in greater detail in Chapter 9 ― Graphics: Images, Widgets, and Drawings.
When graphs are used to explore data, the aim is usually to produce a plot quickly with a minimum of effort. These plots are not designed to look polished but must present the required information as quickly as possible. To produce these graphs, users must learn a simple series of operations which will produce the desired plots. For speed, the most critical operation involves selecting the cells on the spreadsheet which will be used as data before starting the graphing process.
Graphs which are used to present data must be carefully crafted to communicate effectively. Clarity of communication is the critical factor and the plot may include a large amount of work to ensure that the visual result of the plot helps to communicate the desired result.
The use of a graph may not be the best way to communicate information. A verbal explanation or a simple table are often sufficient and, because they are more compact, may be more effective ways to communicate.
Graphs which use a large number of the graphical features available in Gnumeric often appear cluttered. The visual richness of such images can often obscure the message contained in the presentation of the data. Sparse, elegant and direct graphs will communicate results most effectively.