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G492 Eric Rasmusen, erasmuse@indiana.edu14 September 2009 Graphs

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Edward Tufte: The Visual Display of Quantitative

Information (1983)(pictures of numbers) Envisioning Information (1990) (pictures of

nouns) Visual Explanations (1997) (pictures of

verbs). Gary Klass: Just Plain Data Analysis: Finding,

Presenting, and Interpreting Social Science Data (2008)

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Anscombe’s Quartet: The summary statistics are all the same, but graphing them shows how they are different.

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Note the “marginal distribution” on the axes.

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Female cancer rates

Male cancer rates

What do these maps tell us?

8http://www.edwardtufte.com/tufte/minard

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The Deceptive Use of Size

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A Moire pattern (“more- ay”)

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Pie Charts

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(1) Klass uses horizontal bars. Why?

(2) Why is the order of the countries not alphabetical?

FY07 Margin per Credit Hour137.31

103.63

69.99 69.84 68.8659.72 58.00

49.02

16.53 15.10

-90.25

-122.55

-327.04$(330)

$(280)

$(230)

$(180)

$(130)

$(80)

$(30)

$20

$70

$120

Med Sciences HPER COAS Business Optometry SPEA Other Academic

Education SLIS Journalism Law Music Informatics

A Chart with Vertical Bars, a Legend, and a Gray Background

Scaling Effects: Did Unemployment Hardly

Change?

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The Two-Axis Solution to Scaling Effects

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Principles of Graphs 1. Keep the data-to-ink ratio high. 2. Erase data-ink for useless data. 3. Erase non-data ink. 4. Don't use Moire patterns. 5. Use boxes and grids only if they help. 6. Don't use cute pictures that obscure what you are saying. 7. Consider labelling individual data points of special

interest. 8. Write text horizontally, not vertically. 9. Make the figure self-contained. Don't require the reader

to refer to the text or a previous table. Include the source and the units of measurement.

10. Number and title every figure.

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Excel Charts

1. Don’t use a legend (side box with variables being graphed) without good reason. You can often put the variable and units of measurement in the title.

2. Don’t use sideways or vertical writing on the axes

3. Except for dates, use a comma to separate thousands (this is an Excel option under Number).

4. Don’t use a chart area border unless you have good reason.

http://www.rasmusen.org/g492/fed-debt-chart.xls/

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Some Good Graphics

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http://www.edwardtufte.com/bboard/q-and-a-fetch-msg?msg_id=0000SI&topic_id=1&topic=Ask%20E%2eT%2e

New York Times, March 20, 2003, p. D1

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Govt. % of GDP

1970 and 1979

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