Copyright © 2014 Pearson Education, Inc. All rights reserved 1.3 Organizing Categorical Data

1 - 2 Copyright © 2014 Pearson Education, Inc.. All rights reserved. Two-Way Tables  A frequency is the number of times the value is observed in a data set. MenWomen Not Always23 Always47 Gender and Seat Belt Practices

1 - 3 Copyright © 2014 Pearson Education, Inc.. All rights reserved. Two-Way Tables and Frequencies  How many women were surveyed?  Women: = 10  How many from the survey always wear a seat belt?  Always: = 11  How many women from the survey do not always wear a seat belt?  Women AND Not Always: 3 MenWomen Not Always23 Always47 Gender and Seat Belt Practices

1 - 4 Copyright © 2014 Pearson Education, Inc.. All rights reserved. Two-Way Tables and Percentages  What percent are men?  Men: 6/16 =.375  37.5%  What percent always wear a seat belt?  Always: 11/16 =.6875  68.75% MenWomen Not Always23 Always47 Gender and Seat Belt Practices

1 - 5 Percentages to Counts Of the 400 students who were surveyed 65% were carrying their calculators. Of those carrying their calculators, 40% were men.  How many of these 400 students were carrying their calculator?  400 x 0.65 = 260  How many female students were carrying a calculator?  260 x 0.60 = 156 Copyright © 2014 Pearson Education, Inc.. All rights reserved.

1 - 6 Copyright © 2014 Pearson Education, Inc.. All rights reserved. Incomplete Data  There are more basketball injuries than football injuries.  True: 615,546 > 387,948  Basketball is the most dangerous sport among the three listed sports.  This cannot be inferred from the data since we do not know the number of players in each sport. SportNumber of Injuries Baseball178,668 Basketball615,546 Football387,948 Sports Injuries Answer the following true or false.

1 - 7 Copyright © 2014 Pearson Education, Inc.. All rights reserved. Complete Data  Basketball is the most dangerous sport.  Baseball:  Basketball:  Football:  False, football is the most dangerous SportInjuriesPlayers Baseball178,66815,600,000 Basketball615,54628,500,000 Football387,94817,700,000 Sports Injuries Answer the following true or false.

1 - 8 Misleading Statements  China’s total CO2 emissions are higher than America’s, so the Chinese are worse polluters.  Problem: Since there are many more Chinese than Americans, the per capita emissions are higher for Americans.  The government receives more of its total revenue from middle class Americans than from the rich, so the rich are under taxed.  Problem: There are many more middle class Americans. The rich are actually taxed at a higher rate. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Copyright © 2014 Pearson Education, Inc. All rights reserved 1.4 Collecting Data to Understand Causality

Copyright © 2014 Pearson Education, Inc.. All rights reserved. Causality Establishing Causality means to show that an outcome is effected by some treatment.

Anecdotal Evidence is not Science An Anecdote is a story that a single individual tells about his or her own experience. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Observational Studies An Observational Study uses groups that are already created and records the differences.  If an outcome occurs more often with one of the groups than with the other, we say that the treatment and outcome are associated. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Association is not Causation  People with grey hair are observed to have more wrinkles. This does not mean that grey hair causes wrinkles.  A confounding variable is a characteristic other than the treatment that causes both outcomes. For example, old age causes both grey hair and wrinkles. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Controlled Experiment A controlled experiments is an experiment where each individual is assigned to either the control group or the treatment group.  The Treatment Group are the individuals who receive the treatment  The Control Group are the individuals who do not receive the treatment. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Placebo Effect  The placebo effect is the phenomenon of reacting after being told of receiving a treatment even if there was no actual treatment given. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Blind and Double Blind Study  A blind study is a control study where the participants do not know whether they are in the control group or the treatment group.  A double blind study is a blind study where the person administering treatment also does not know who is in the control group and who is in the treatment group. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Random Assignment not Bias  Bias may occur when the assignments are not random and the results are influenced in a particular direction. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Copyright © 2014 Pearson Education, Inc. All rights reserved Chapter 1: Case Study Deadly Cell Phones

Case Study  Dr. Christopher Newman sued claiming that cell phone use caused his brain tumor.  Suit cited a TV show where a man’s wife used a cell phone often and died of a brain tumor.  Suit also cited a study of people who recovered from brain tumors.  The study found a high percent of cell phone users from the brain tumor inflicted population. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Anecdotal Evidence  Citing a single person as evidence that cell phone use causes brain tumors is anecdotal evidence.  One cannot conclude anything about the whole population from anecdotal evidence of a single person.  This piece of the doctor’s argument is completely invalid. Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Problems With the Study Cited  Participants were not assigned to use or not use a cell phone.  Looking at brain cancer survivors only excludes all who did not survive.  A follow-up control study with mice did not agree with the original study Copyright © 2014 Pearson Education, Inc.. All rights reserved.

Conclusion of Lawsuit  The judge ruled that the evidence was insufficient.  Evidence did not establish a causal relationship between cell phone use and brain tumors.  The judge threw out the case. Copyright © 2014 Pearson Education, Inc.. All rights reserved.