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Chapter 10. Graphs, Good and Bad. Thought Question 1. What is confusing or misleading about the following graph?. Distribution. Tells what values a variable takes and how often it takes these values Can be a table, graph, or function. Variables. Categorical
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Chapter 10 Graphs, Good and Bad Chapter 10
Thought Question 1 What is confusing or misleading about the following graph? Chapter 10
Distribution • Tells what values a variable takes and how often it takes these values • Can be a table, graph, or function Chapter 10
Variables • Categorical • Places an individual into one of several groups or categories • Display distribution with a bar graph or a pie chart • Quantitative (Numerical) • Takes numerical values for which arithmetic operations such as adding and averaging make sense Chapter 10
Easy or difficult to achieve hypnotic trance Group assignment Pre-study white blood cell count Post-study white blood cell count Case Study (from Ch.1) The Effect of Hypnosis on the Immune System categorical quantitative Chapter 10
Age (in 1976) Weight in 1976 Weight at age 18 Incidence of coronary heart disease Other: smoking, family history, menopausal status, post-menopausal hormone use. Case Study (from Ch.1) Weight Gain Spells Heart Risk for Women quantitative categorical Chapter 10
Class Make-up on First Day(Summer 2002) Data Table Chapter 10
Class Make-up on First Day(Summer 2002) Pie Chart Chapter 10
Class Make-up on First Day(Summer 2002) Bar Graph Chapter 10
Line Graphs • A line graph shows behavior over time. • Time is always on the horizontal axis. • Look for an overall pattern (trend). • Look for patterns that repeat at known regular intervals (seasonal variations). • Look for any striking deviations that might indicate unusual occurrences. Chapter 10
Class Make-up on First Day(Fall Semesters: 1985-1993) Chapter 10
Source: State of the York Watershed 2000, The York Watershed Council, Virginia Beware of Pictograms Chapter 10
Another Misleading Graph Chapter 10
Making Good Graphs • Title your graph. • Make sure labels and legends describe variables and their measurement units. Be careful with the scales used. • Make the data stand out. Avoid distracting grids, artwork, etc. • Pay attention to what the eye sees. Avoid pictograms and tacky effects. Chapter 10
Key Concepts • Categorical and Quantitative Variables • Distributions • Pie Charts • Bar Graphs • Line Graphs • Techniques for Making Good Graphs Chapter 10