Writing and Publishing Scientific Articles
8-16
When there is a need to compare 2 or more wholes, you should use bar graphs with segments (corresponding to the wedges of a pie graph) rather than pie graphs because the angular areas of the wedges of the pies may make comparisons difficult. Additionally, some journals may discourage or not allow the use of pie graphs, although such figures are common in nonscientific publications.
Chlorine (2%)
Fluorine (3%)
Hydrogen (20%)
Nitrogen (45%)
Oxygen (25%)
Figure 12. Composition of gas used in study.
The legend for this pie graph is brief because the figure is largely self- explanatory.
Graph Guidelines
In addition to the advice given above for each type of graph, please consider the following when preparing graphs.
Keep your graphs simple. Be selective about which PowerPoint or Excel features you use. The primary goal of a graph is easy understandability. Therefore, avoid cluttering a graph with more than 3 or 4 curves. And use 3 dimensions only if you are plotting 3 variables. When the bars in a graph are 3-dimensional, readers are unable to figure out where to read the y-axis values.
Label the axes on your graphs so that readers can tell what variable is shown on each axis and what the units of measure are.
Consider your t arget journal’s color guidelines in deciding how to differentiate between multiple bars or lines on graphs. Use colors, shades of gray, or black and white patterns that are easy to tell apart and, ideally, that reproduce well if printed in black and white.
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