1. Slide Slide 1 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley. Created by Tom Wegleitner, Centreville, Virginia Edited by Olga Pilipets, San Diego, California Critical Thinking

2. Slide Slide 2 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley. Key Concepts  Success in the introductory statistics course typically requires more common sense than mathematical expertise.  This section is designed to illustrate how common sense is used when we think critically about data and statistics.

3. Slide Slide 3 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley. Misuses of Statistics

4. Slide Slide 4 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley. Misuse # 1- Bad Samples  Voluntary response sample (or self-selected sample) one in which the respondents themselves decide whether to be included In this case, valid conclusions can be made only about the specific group of people who agree to participate.

5. Slide Slide 5 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley. Misuse # 2- Small Samples Conclusions should not be based on samples that are far too small. Example: Basing a school suspension rate on a sample of only three students

6. Slide Slide 6 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley. To correctly interpret a graph, you must analyze the numerical information given in the graph, so as not to be misled by the graph’s shape. Misuse # 3- Graphs

7. Slide Slide 7 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley. Part (b) is designed to exaggerate the difference by increasing each dimension in proportion to the actual amounts of oil consumption. Misuse # 4- Pictographs

8. Slide Slide 8 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley. Misuse # 5- Percentages Misleading or unclear percentages are sometimes used. For example, if you take 100% of a quantity, you take it all. Example: a certain airline company claimed that they increased the recovery of missing luggage by up to 100%

9. Slide Slide 9 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley.  Loaded Questions  Order of Questions  Refusals  Correlation & Causality  Self Interest Study (who is paying for the study?)  Precise Numbers  Partial Pictures  Deliberate Distortions Other Misuses of Statistics

10. Slide Slide 10 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley. Recap  Reviewed 13 misuses of statistics  Illustrated how common sense can play a big role in interpreting data and statistics In this section we have:

11. Slide Slide 11 Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley.

12. Slide Slide 12 Percentages Key principal: Percentage of What is 34% of 500? Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley.

13. Slide Slide 13 Percentages Fraction to a percentage Convert to percentage. Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley.

14. Slide Slide 14 Percentages Decimal to a percentage Convert 0.789 into percentage. Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley.

15. Slide Slide 15 Percentages P ercentage to a decimal Convert 56.7% to an equivalent decimal.. Copyright © 2007 Pearson Education, Inc Publishing as Pearson Addison-Wesley.