Guidelines for Technical Writing

by V.L. Young and K.J. Sampson

Figures

General Rules - Rules for Graphs - Examples

General Rules (Return to top)

  • Must have a caption such as "Figure 1. Ethylene glycol process flowsheet."
  • Must be numbered in the order they appear.
  • Must be discussed in the text. If it's not important enough to mention, it's not important enough to show.
  • Must appear no later than the page following the first reference in the text.
  • Must be referred to using a capitalized name (Figure 1).
  • Must identify units for any numbers on it.
  • Must have its top closest to the top of the page if "portrait", or the bound side of the page if "landscape."
  • Must have a proper margin outside the title and labels, not just around the picture.
  • Should stand alone as much as possible. (Label streams, units, dimensions, components.)
  • Meaning or importance should be described in text.

    • Rules for Graphs (Return to top)

    The Plots

  • If your reader is supposed to compare multiple plots, put them on the same graph. If the result is too cluttered and you must use different graphs, at least keep the scales consistent so they can be easily compared.
  • Use different shapes and line types to distinguish multiple plots on the same graph. Color will be lost if your graph is reproduced in black-and-white.
  • Don't connect the dots.
  • Draw curves with a straight edge, spline, or French curve, or fit an equation to the data.
  • Use symbols, not dots, for your data.
  • Include error bars.
  • When using spreadsheets for plots, select "scatter" or "x-y" plots, not "line" plots. Your tick marks should be evenly spaced, but not necessarily your data points.
  • Make your legend meaningful.

    • The Axes

  • Label the axes with descriptive word(s) and units.
  • Spread out data by appropriate axis scaling. The axis need not start at zero unless it is important to show the intercept.
  • Major tick marks should have appropriate labels, such as multiples of 1, 2, 5, or 10.
  • Minor divisions of the axis should be appropriate. (eg. 5/5 but not 5/6; An example is coming.)
  • Use scientific notation with units when appropriate. Be careful about the sign on the exponent. (An example is coming.)
  • Use as few digits as possible. The precision of the reading depends on the graph divisions, not the number of trailing zeroes. (An example is coming.)

    • Examples (Return to top)

    Examples are coming.

  • Return to top.
  • Return to Guidelines.
  • Return to Dr. Young's home page.
  • Return to Chemical Engineering home page.

    • (Last modified on 5/08/98)