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1 G492 Eric Rasmusen, 14 September 2009 Graphs.

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Presentation on theme: "1 G492 Eric Rasmusen, 14 September 2009 Graphs."— Presentation transcript:

1 1 G492 Eric Rasmusen, 14 September 2009 Graphs

2 2 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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4 4 Anscombes Quartet: The summary statistics are all the same, but graphing them shows how they are different.

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6 6 Note the marginal distribution on the axes.

7 7 Female cancer rates Male cancer rates What do these maps tell us?

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10 10 The Deceptive Use of Size

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14 14 A Moire pattern (more- ay)

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18 Pie Charts 18

19 19 (1) Klass uses horizontal bars. Why? (2) Why is the order of the countries not alphabetical?

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

21 Scaling Effects: Did Unemployment Hardly Change? 21

22 The Two-Axis Solution to Scaling Effects 22

23 23 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.

24 24 Excel Charts 1. Dont 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. Dont 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. Dont use a chart area border unless you have good reason.

25 25 Some Good Graphics

26 26 msg?msg_id=0000SI&topic_id=1&topic=Ask%20E%2eT%2e msg?msg_id=0000SI&topic_id=1&topic=Ask%20E%2eT%2e New York Times, March 20, 2003, p. D1

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28 28 Govt. % of GDP 1970 and 1979

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