Tables and figures enable authors to present a large amount of information efficient ly and to make their data more comprehensible. Tables usually show numerical values or textual information (e.g., lists of stimulus words) arranged in an orderly display of columns and rows. A figure may be a chart, a graph, a photograph, a drawing, or any other illustration or nontextual depiction. At times the boundary between tables and fig ures may be unclear; however, tables are almost always characterized by a row-column structure. Any type of illustration other than a table is referred to as a figure. In this chapter, we discuss the purposes that data displays can serve and provide guidance on designing and preparing data displays so that they communicate most effectively. We provide specific guidance on formatting and constructing tables and fig ures, along with a number of illustrative examples.

General Guidance on Tables and Figures 5.01 Purposes of Data Displays Data displays can serve several purposes: exploration: the data contain a message, and you would like to learn what it is (exploratory data analysis and data mining techniques are examples of displays that are principally exploratory); 1 GENERAL GUIDANCE ON TABLES AND FIGURES communication: you have discovered the meaning contained in the data ~nd want to tell others about it (this is the traditional purpose of most data displays m sCientific documents); calculation: the display allows you to estimate some statistic or function of the data (nomographs are the archetype of this); storage: you can store data in a display for retrieval later, including the res~lts of a study for later use in a meta-analysis (historically, this. r?le has been fulfilled by tables, but figures sometimes serve this purpose more effiCiently); and

In scientific publication, the communication function of graphical displays dOn;'inates; however, other features (e.g., storage) may be useful in a graphical representatIOn.

5.02 Design and Preparation of a Data Display The first step in preparing a display for submission is to determine the purp?ses of the display and the relative importance of those purposes. For example, the det~il reqUired for a storage display may conflict with the clanty reqUired for a commumcatlve one. Once you have decided on a display's hierarchy of purposes, choose the template best designed for its primary purpose-the canonical form of a display .. Such a display (e.g., a scatterplot) has shown itself to be flexible (it works for many kmds of data), robust (it works reasonably well even when it is not exactly SUitable), and adaptive (It sh~ws a capacity for adaptation to make it suitable). Further, the use of canomcal forms sim plifies the task of readers trying to make sense of a display because they can rely on past experience with the form.