W3A. Figures and Tables in Academic Writing

1. Summary

1.1 Why Use Visuals in Academic Writing?

Visuals—including figures, tables, graphs, and diagrams—are not decorative elements in academic writing. They serve specific communicative functions that text alone cannot perform as efficiently. Well-chosen visuals:

• Capture and hold the reader’s attention
• Illustrate textual information and data in a more accessible form
• Simplify complicated textual descriptions that would be difficult to follow in prose
• Help readers understand complex systems, processes, and data relationships at a glance

The key principle is that visuals should supplement the text, not replace it. Every visual must be referenced and briefly discussed in the surrounding text.

1.2 Types of Visuals and Their Purposes

Different visual formats serve different communicative purposes. Choosing the right type depends on what kind of information you want to convey:

Visual type	Best used to
Photograph	Show actual appearance of objects, specimens, or environments
Block diagram	Show the relationship of components in a system or process
Table	Present exact numerical information or organize complex categorical data
Line graph	Show dynamic comparison or change over time (continuous data)
Scatter plot	Show correlation between two variables
Bar graph	Compare data when there is no evidence of a continuum (discrete categories)
Pie chart	Compare parts of a whole (proportions that sum to 100%)
Box plot	Display differences between datasets, showing central value, variability, and range

Selecting the wrong visual type creates confusion. For example, using a pie chart to show change over time is misleading—a line graph is the correct choice for temporal data.

1.3 Guidelines for Figures

A figure is any visual element that is not a table—graphs, photographs, diagrams, flowcharts, and maps are all figures. When creating or incorporating figures, follow these principles:

• Use figures to show trends and relationships, not to present raw numbers (use a table for that).
• Axis placement: For graphs and bar charts, place the independent variable on the x-axis and the dependent variable on the y-axis.
• Readability: Make each figure easy to read at a glance. Avoid clutter, excessive gridlines, and overlapping labels.
• Differentiation: If your figure contains multiple data series (e.g., multiple lines on a graph), differentiate them clearly using distinct colors, line styles, or markers.
• Label axes and scales clearly: Every axis must have a label and unit of measurement.
• Caption content: The caption should include what, where, and when information. A caption is not just a title—it should help a reader who is browsing the paper understand the figure without reading the full text.

Caption format (IEEE style):

Fig. 1. Caption text describing the figure.

• Place the caption below the figure.
• Always abbreviate “Figure” as “Fig.” when referring to it in the text (e.g., “As shown in Fig. 1…”).

1.4 Guidelines for Tables

A table organizes information into rows and columns. Tables are appropriate when you need to present precise numbers or organize data that is too detailed or complex to describe clearly in prose.

Key principles for effective tables:

• Information flow: Place familiar, contextual information on the left and new, important information on the right. Readers naturally scan left-to-right, expecting context first and new data second.
• Numbering: Tables are numbered separately from figures, using Roman numerals (TABLE I, TABLE II, TABLE III…).
• Caption placement: Unlike figures, table captions are placed above the table.
• Caption format: Captions are formatted as an inverted pyramid (longest line first, progressively shorter lines). No full stop at the end.
• Precision: Avoid including redundant columns or rows. Every piece of information in the table should be necessary.

Example of weak vs. strong captions:

Weak caption	Strong caption
Table I. Characteristics of Intestinal Flora	Table I. Characteristics of Intestinal Flora Found for 21 Patients with HIV-I
Table II. Soil Analysis	Table II. Soil Analysis of Six Farm Fields Near Urban Development Zones

The stronger captions specify the scope, population, and context of the data—making the table self-explanatory.

1.5 Figures and Tables in the Method Section

In a systematic literature review, a particularly common and useful figure is the literature flow diagram—a visual representation of how many papers were found, screened, and included at each stage of the review process. This type of figure:

• Makes the selection procedure transparent
• Helps readers quickly grasp the scale of the review
• Demonstrates methodological rigor

Similarly, the inclusion/exclusion criteria table in the Method section is a standard element of systematic reviews. It lists the criteria used to decide which papers were kept and which were discarded, organized by facet (e.g., language, publication type, date range, topic relevance). A well-formatted criteria table allows readers to evaluate whether the criteria were appropriate and consistently applied.