1. Making Graphs

2. The Basics … Graphical Displays Should: induce the viewer to think about the substance rather than about the methodology, graphic design, the technology of the graphic production, or something else avoid distorting what the data have to say present many numbers in a small space Continued...

3. The Basics … Graphical Displays Should: (2) make large data sets coherent encourage the eye to compare different pieces of data serve a clear purpose be closely integrated with the statistical and verbal descriptions of a data set.

4. Lie Factor Lie Factor = size of effect shown in graphic size of effect in data Greater than 1.05% or less than.95% indicates substantial distortion, far beyond minor inaccuracies in plotting.

5. NYT: Fuil economy “graph”

6. The eye perceives area, not height

8. Maps: just bad graphs

15. Chartjunk What is it? Anything that doesn’t NEED to be included in the chart. To clean-up chartjunk, watch your data-ink ratio. “Data-ink is the non-erasable core of a graphic, the non-redundant ink arranged in response to a variation in the numbers represented.” Data-ink ratio = data-ink total ink used to print the graphic

18. Some cool historical graphs 1. Planetary orbits, 10 th or 11 th century

19. William Playfair (1759-1823) Inventor of: Line graph Bar graph Pie chart

20. Trade balance of England

21. Imports and exports of Scotland

22. Playfair: area of countries (circles), population (left line seg.) and tax revenue (right line seg.).

23. U.S. age pyramids, 1874

24. Minard's Napoleon's March to Moscow

25. Tufte principles: Show Data Focus on Content instead of graphic production Avoid Distorting what Data has to say Make Large Data Sets Coherent Encourage Eye to Compare Different Pieces of Data Reveal Data at several Levels of Detail Closely integrate Statistical and Verbal Descriptions

26. Line Graph –x-axis requires quantitative variable –Variables have contiguous values –familiar/conventional ordering among ordinals Bar Graph –comparison of relative point values Scatter Plot –convey overall impression of relationship between two variables Pie Chart –Emphasizing differences in proportion among a few numbers

27. Bar charts Best for comparing different things during the same time period Neither the bars nor the axis should be interrupted Axis should usually include zero (some exceptions) Avoid 3-D effects, can be misleading

28. Line graphs Best for showing change over time Can indicate trends Use a different color and symbol for each line Avoid too many lines When to use log scale

29. Percent of Persons Aged 65+ Residing with their Own Children aged 18+: United States 1850-2000 Labeling: Title Height/width should be about 3:4 (same as old- fashioned TV Labeling: lines

30. Percent of the Labor Force Employed in Agriculture, United States, 1800-2000

31. Figure 1: Percent of elders in intergenerational families Too many lines!

32. 0 5 10 15 20 25 30 35 40 45 50 1960196519701975198019851990199520002005 Percent in Labor Force Mexico Costa Rica Ecuador Chile Venezuela Colombia Brazil Married Female Labor Force Participation in Latin America (age 18 to 65)

33. 0 10 20 30 40 50 60 70 1920193019401950196019701980199020002010 Percent in Labor Force Latin America United States Married Female Labor Force Participation: Latin America and U.S. (age 18 to 65)

34. 0 10 20 30 40 50 60 70 1920193019401950196019701980199020002010 Percent in Labor Force United States Mexico Costa Rica Ecuador Chile Venezuela Colombia Brazil Married Female Labor Force Participation: Latin America and U.S. (age 18 to 65) Compare Latin America to U.S. 40 years ago

35. Married Female Labor Force Participation: Mexican-born Women, 1970-2000 0 10 20 30 40 50 60 70 1970197519801985199019952000 Percent in Labor Force Mexican-born Women in United States Women in Mexico

39. Percent deviation in intergenerational coresidence of each occupational group from nonfarm average: Younger generation

40. IPUMS Graph from “A Century of Women in Science and Engineering,” History Day project by Abby Norling- Ruggles, age 12