Essentials of Biostatistics. 5. Graphical methods to summarize data

Abstract

The previous article of this series(1) includes the numerical methods to summarize data. For visual display, graphs, diagrams, charts and maps are commonly used. They are generally referred to as "figure" in the literature, though this includes nondata based pictures also such as of a bone or a lesion. Visual display is considered a powerful medium for communica-tion. The impression received from such figures seems to be more vivid and lasts longer than the impression from numeric data. Section 5.1 includes graphs for representing frequency distribution. Graphs for nominal and ordinal data are presented in Section 5.2. Graphs for depicting the relation between two variables of metric type are given in Section 5.3. Some special diagrams used in health and medicine are described in Section 5.4. The last section describes some cautions needed in visual display.