Exam 1: Statistics Success Stories and Cautionary Tales

A newspaper reported that 41% of students who had taken calculus in high school had a college freshman year GPA (grade point average) of 3.2 or higher. The headline was "High School Courses Key to College Grades". One potential problem with this headline is

Use the following information for questions: According to a CNN poll released in January of 2010, 56 percent of the public opposed the stimulus bill, with 42 percent supportive of the plan. The CNN/Opinion Research Corporation poll was conducted January 8-10, with 1,021 adult Americans questioned by telephone. The survey's sampling error was reported as plus or minus 3 percentage points. -How many people in the sample opposed the stimulus bill?

Use the following information for questions: The table below shows the results of a survey of students who took college prep courses who were asked to rate their high school education. -Calculate the percentage of students who gave a good rating to their high schools.

In the study described in Case Study 1.4, questionnaires were sent to 100,000 women asking about love, sex and relationships. Only 4.5% of the women responded. This means that

Use the following information for questions: Gallup's standard of living measure reports the percentage of Americans who say their standard of living is getting better versus the percentage who say their standard of living is getting worse. Results are based on telephone interviews with approximately 3,000 national adults. The margin of error is reported as ±2 percentage points. In January of 2011, 49% reported that their standard of living is getting better. -Provide an interval of numbers that is 95% certain to cover the true percentage of Americans who report that their standard of living is getting better.

A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants' blood pressure over the year was measured, and the change was compared for the two groups. -If a statistically significant difference in blood pressure change at the end of a year for the two activities was found, then

Use the following information for questions: In a study of patients who had a heart attack, 3630 patients were randomly assigned to receive one of three treatments: aspirin alone, warfarin alone, or aspirin plus warfarin. The results showed that 20.0% of the aspirin group had another heart attack, stroke, or died, compared with 16.7% of the warfarin group and 15.0% of the aspirin plus warfarin group. The difference between the aspirin and warfarin groups was statistically significant, while the difference between the warfarin and aspirin plus warfarin group was not statistically significant. -The statistically significant difference between the aspirin group (20.0%) and the warfarin group (16.7%) means that

Use the following information for questions: In a 1994 Census Bureau report, the total number of households and the number of households with a married couple and their own children were reported for the years 1990 and for 1994. The results are given below: One newspaper reported these results with the following headline: "Number of Two-Parent Families Up." Another newspaper, based on the percentages, reported on the same results with the headline: "Traditional Families Less Common". -Both newspapers reported correct figures; explain why it was possible for them to come to opposite conclusions. Which conclusion do you think is more descriptive of the trend?

In 1992, the total number of deaths among American men aged 15-19 was 10,747, with 3,664 deaths among American women aged 15-19 years. The total numbers of 15-19 year olds were 8.78 million men and 8.33 million women. Calculate the death rates per 100,000 for 15-19 year old men and women. Was the rate for men higher or lower than for women?

In the Sydney 2000 Olympics, Cathy Freeman (Australia) won the gold medal in the women's 400 meter event. Lorraine Graham (Jamaica) won the silver medal, and Katharine Merry (Great Britain) won the bronze. The times (in seconds) of the 8 finalists are listed below. Calculate the five-number summary for the women's 400 meter final. 49.11 $\quad$ 49.58 $\quad$ 49.72 $\quad$ 49.79 $\quad$ 49.96 $\quad$ 50.05 $\quad$ 50.12 $\quad$ 51.04

In the presidential election of 1936, the Democratic incumbent Franklin Roosevelt was re-elected over the Republican challenger Alf Landon. Before the election, the magazine Literary Digest had published the results of a questionnaire sent to 10 million people: 2.3 million people chose to reply to the survey. The poll incorrectly predicted that Landon would win the election. Explain why this prediction was inherently unreliable.

A pop quiz in a class resulted in the following eight quiz scores: 0, 60, 66, 78, 82, 96, 98, 100. The five-number summary for these test scores is

A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants' blood pressure over the year was measured, and the change was compared for the two groups. -The two treatments in this study were

In 2001 the baseball player Barry Bonds had 156 base hits out of 476 at bats. In 1986, Bond's first season, he had 92 hits out of 413 at bats. Calculate Bond's batting average (ratio of base hits to times at bat) for the 2001 and 1986 seasons.

A sociologist has been studying college instructors and is especially interested in those instructors who teach night classes. He has been collecting data for years. Some of the variables are the course grade from the student evaluations, the number of students who take the course, the age of the instructor, the income of the instructor, the field of the course (social sciences, natural sciences, humanities, music/arts), the highest level of education the instructor has completed (Bachelor, Master, Ph.D.). The sociologist has looked at relationships between many of the variables and tested if there were differences between the different fields. The only difference that was found to be significant was the mean age of social science instructors and the mean age of natural science instructors. What is most likely the cause of this one significant result?

Which of the following is true about the margin of error for the most common types of surveys?

Which of the following is not a component of "Statistics"as defined in Chapter 1?

An Islamic survey conducted by the Gallup organization consisted of a random sample of 10,004 people living in 9 predominantly Islamic countries. The sample was collected by interviewers going to people's homes in randomly chosen areas in each of the 9 countries. The population represented by this sample was

Drawn below are two dotplots displaying the dollar amount spent on textbooks for one semester for 36 female and 39 male students at Penn State University. Also given are the five number summaries. Describe any differences or similarities between the two sets of data.

Use the following information for questions: The next three questions are based on a study (part of the Women's Health Initiative) of healthy women volunteers. A total of 16,608 women were randomly assigned to take either placebo or a popular hormone replacement therapy (HRT) for eight years. The study was stopped after 5 years in part because the women on HRT had a higher rate of heart attacks than the placebo group. -The rate of heart attacks for women on HRT was 29% higher than the rate in the placebo group. The baseline rate of heart attacks in the placebo group was 30 per 10,000 women. What was the rate of heart attacks in the HRT group?