Copyright © 2010, 2007, 2004 Pearson Education, Inc. - use pie charts, bar graphs, and tables to display data Chapter 3: Displaying and Describing Categorical Data

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Frequency Tables People aboard the Titanic:

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Relative Frequency Tables Gives percentages of classes on the Titanic:

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Both tables show the distribution (possible values) among classes on the Titanic

Copyright © 2010, 2007, 2004 Pearson Education, Inc. What’s Wrong With This Picture? It makes it look like the crew made up more than half the members aboard

Copyright © 2010, 2007, 2004 Pearson Education, Inc. The Area Principle The area occupied by a part of the graph should correspond to the value it represents. Bar graphs are good for this

Copyright © 2010, 2007, 2004 Pearson Education, Inc. What’s wrong with this display?

Copyright © 2010, 2007, 2004 Pearson Education, Inc. This plot of the percentage of high-school students who engage in specified dangerous behaviors has a problem. Can you see it? What’s wrong with this display?

Copyright © 2010, 2007, 2004 Pearson Education, Inc. What’s wrong with this display?

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Thus, a better display for the ship data is:

Copyright © 2010, 2007, 2004 Pearson Education, Inc. A relative frequency bar chart displays the relative proportion of counts for each category.

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Contingency Tables allow us to look at two categorical variables together (how values are distributed for one variable, given another).

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Marginal Distributions Values in the margins:

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Conditional Distributions Values inside the table, not in the margins:

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Segmented Bar Charts A segmented bar chart, a pie chart in bar form each bar adds to 100% divided proportionally by each conditional cell

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Independence or Association? the distribution of classes for the survivors is different from the non-survivors Conclusion: Class and Survival are not independent. Not independent = association Independent = no association **if the distribution of alive/dead by class was the same = class/survival would be independent

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Example 1: Music Pref./Gender

Copyright © 2010, 2007, 2004 Pearson Education, Inc. Example 2: Video Games/Facebook

Copyright © 2010, 2007, 2004 Pearson Education, Inc.

Ch.3 Assignment (pg.38) # 5, 7, 9, 13, 15, odd, 31, 37(omit f)