General guidelines for how to include a figure in a scientific paper?

Question

I am supervising a project by a group of students who are quite new to academic/scientific writing. I have now read a draft of their report, and noticed the following errors in regards to how they use figures:

1. The meaning of the y-axis is shown in the title, rather than as a y-axis label.
2. The x-axis label is shown on the right of the x-axis tick values.
3. The legend contains information that should be in the y-axis label, e.g., Policy 1 inventory level, Policy 2 inventory level.
4. The figures are placed in the middle of the text without a figure number and a caption.

My question is: Is there is a good reference or set of guidelines which I could pass to the students to help them to learn how to properly include figures in their report?

Answer 1

Though the question refers to "including" graphs, the issues seem to be matters of labelling and presentation, which are part of graph design as a whole. The following are "the principles of graph construction" from William S. Cleveland's excellent if dated "The Elements of Graphing Data" (Wadsworth, 1985).

CLEAR VISION:

• Make the data stand out. Avoid superfluity.
• Use visually prominent graphical elements to show the data.
• Use a pair of scale lines for each variable. Make the data region the interior of the rectangle formed by the scale lines. Put tick marks outside the data region.
• Do not clutter the data region.
• Do not overdo the number of tick marks.
• Use a reference line when there is an important value that must be seen across the entire graph, but do not let the line interfere with the data.
• Do not allow data labels in the data region to interfere with the quantitative data or to clutter the graph.
• Avoid putting notes, keys, and markers in the data region. Put keys and markers just outside the data region and put notes in the legend or in the text.
• Overlapping plotting symbols must be visually distinguishable.
• Superposed data sets must be readily visually discriminated.
• Visual clarity must be preserved under reduction and reproduction.

CLEAR UNDERSTANDING:

• Put major conclusions into graphical form. Make legends comprehensive and informative.
• Error bars should be clearly explained.
• When logarithms of a variable are graphed, the scale label should correspond to the tick mark labels.
• Proofread graphs.
• Strive for clarity.

SCALES:

• Choose the range of the tick marks to include or nearly include the range of the data.
• Subject to the constraints that scales have, choose the scales so that the data fill up as much of the data region as possible.
• It is sometimes helpful to use the pair of scale lines for a variable to show two different scales.
• Choose appropriate scales when graphs are compared.
• Do not insist that zero always be included on a scale showing magnitude.
• Showing data on a logarithmic scale can improve resolution.
• Use a scale break only when necessary. If a break cannot be avoided, use a full scale break. Do not connect numerical values on two sides of a break.

GENERAL STRATEGY:

• A large amount of quantitative information can be packed into a small region.
• Graphing data should be an iterative, experimental process.
• Graph data two or more times when it is needed.
• Many useful graphs require careful, detailed study.