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7.021 Meeting 3: Illustrations7.021 Meeting 3: Illustrations

What’s the Purpose of Illustrations?What’s the Purpose of Illustrations?

• Condense large amounts of information

• Convince readers of your findings (by showing dataquality).

• Focus attention on certain findings (e.g., relationshipbetween values).

• Simplify complex findings.

• Promote thinking and discussion.

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Other PurposesOther Purposes• Illustrate (with photomicrographs, line drawings,

computer-generated images, etc.):– Morphology– Pathological findings– Experimental design– Models– Apparatus

• Get your gorgeous illustration on the cover of thejournal.

Choose the Most Effective Type ofIllustration for a Given Goal

from Successful Scientific Writing, 2nd ed.

Choose the Most Effective Type ofIllustration for a Given Goal

from Successful Scientific Writing, 2nd ed.

To accomplish this:• To present exact values, raw data,

or data which do not fit into anysimple pattern.

• To summarize trends, showinteractions between two or morevariables, relate data to constants,or emphasize an overall patternrather than specific measurements.

• To dramatize differences or drawcomparisons.

• To illustrate complex relationships,spatial configurations, pathways,processes, or interactions.

• To compare or contrast.

Choose one of these:• Table, list

• Line graph

• Bar graph

• Diagram

• Pictograph, pie chart, bar graph

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Choose the Most Effective Type ofIllustration (cont.)

from Successful Scientific Writing, 2nd ed.

Choose the Most Effective Type ofIllustration (cont.)

from Successful Scientific Writing, 2nd ed.

To accomplish this: Choose one of these:• To show sequential processes. Flowchart• To classify information. Table, list, pictograph• To describe parts or circuits. Schematic• To describe a process, organization, or Pictograph, flowchart, block

model. diagram.• To describe a change of state. Line graph, bar graph• To describe proportions. Pie chart, bar graph• To describe relationships. Table, line graph, block diagram• To describe causation. Flowchart, pictograph• To describe an entire object. Schematic, drawing, photograph• To show the vertical or horizontal Flowchart, drawing tree, block

hierarchy within an object, idea, or diagram.organization.

Provide Textual Context forYour Illustrations

Provide Textual Context forYour Illustrations

In the body of your article:• Refer explicitly to the illustration (e.g., “see Table 1,”

“refer to Figure 3.”)• Tell the reader:

– How the graphic advances, supports, clarifies, orsummarizes your discussion.

– Why it is important.– What it means.– How it supports your argument.

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Creating TablesCreating Tables

• Paradis and Zimmerman 1988, p 68

Useless Table #1Useless Table #1

These data should be presented in text:“Aeration of the growth medium was essential for the growth of S. coelicolor.

At room temperature (24’C) no growth was evident in stationary cultures,whereas substantial growth (D, 78 Klett units) occurred in shaken cultures.”

What else is wrong with this table?

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Useless Table #2Useless Table #2• This data has a suspicious number

of zeros. (Watch also for repetitive100’s when expressing percents).

• It should be presented in text:– The oak seedlings grew at

temperatures between 20 and40’C; no measurable growthoccurred at temperaturesbelow 20’ C or above 40’C.

• “When a table or column canreadily be put into words, do it.”R.A. Day

Useless Table #3Useless Table #3

• Beware of plus and minus signs.• This table simply says:

– “S. griseus, S. coelicolor, S. everycolor, and S. rainbowenski grewunder aerobic conditions, whereas S. nocolor and S. greenicusrequired anaerobic conditions.”

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How to Arrange TablesHow to Arrange Tables• Arrange data so like elements

read:– down (fig 7)– not across (fig 6)

• To illustrate, try addingnumbers across.

A Good TableA Good Table

• Title (Heading):– Concise - just one sentence or clause.

• Headings (Columnhead and Subheads):– Clear enough to make data understandable without having to look at the text.– Abbreviations in headings (e.g., temp) conserve space

• Footnotes:– Give just enough detail to make data understandable and do not repeat

experimental detail.– Spell out abbreviations used in body of the table.

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Types of GraphsTypes of Graphs

More GraphsMore Graphs

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When to Use GraphsWhen to Use Graphs• Use graphs to present data in an

organized way, not to dress it up.– Don’t use both table and graph for the

same data.

– Use line graphs for data that showpronounced trends.

– Use bar and dot charts to show itemswith different values.

A Useless GraphA Useless Graph

This useless bar graph should be presented in text:– “Among the test group of 56 patients who were hospitalized for an

average of 14 days, 6 acquired infections.”

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A Good GraphA Good Graph• Lettering large enough to

withstand photographicreduction.

• Sides are boxed rather thantwo-sided so right-hand valuesare easy to estimate.

• Scribe marks point inward.

• Legend:– Concise title– Defines symbols– Provides information pertinent to

data interpretation.

What are Some Pitfalls ofFigures and Legends?

What are Some Pitfalls ofFigures and Legends?

• Figures:– Not mentioned in text.– Textual data inconsistent with figures.– Mislabeling.– Symbols, data points, unreadable or cluttered.– Ugliness (failure to get help from graphic designer).

• Legends:– Reiterate results section– Written in shorthand, abbreviated form rather than

whole sentences.

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Today’s In-Class ExercisesToday’s In-Class Exercises1. Respond to Stellar Discussion Topic for Meeting 4.2. For the experimental data distributed in class:

a) Put the data in the form of a table.b) Then, put the same data in the form of a graph.c) Write a figure legend for the graph.d) Indicate the form that you think best displays the data

and explain your reasoning.3. Two illustrations will be distributed in class. Note their

deficiencies for class discussion.4. Begin to prepare two figures for results from your current

laboratory experiments (choose data to illustrate, sketchout illustration). Consider what information you willinclude in the figure legends. Make a mock-up illustration.

Today’s Out-of-Class ExercisesToday’s Out-of-Class Exercises

• Complete the two figures from your current lab modulethat you began in class. Use the tool that suits you best,e.g., computer graphics, paper graphics, power point, etc.Don’t forget to include figure legends.

• Look in the published literature for one example of a goodfigure and one example of a poor figure. Print orphotocopy them and bring them to the next class. Be readyto discuss your choices.

• Create two illustrations (tables, graphs, or figures) for yourlong-term project.

• Revise introduction to long-term project as indicated.