Exam 1: Statistics Success Stories and Cautionary Tales

Drawn below are two dotplots displaying the heights (in inches) of 94 females and 77 males. Also given are the 5 number summaries. Describe any differences or similarities between the two sets of data.

Use the following information for questions: A five number summary for hours studied in a week were 5, 12, 14, 18, and 20. -What was the longest number of hours studied by anyone?

Use the following information for questions: The results of 2,475 people on trial for murder are shown below by the race of the victim (black or white) and the verdict (death penalty yes or no). These results were used in a Supreme Court trial on behalf of a defendant. -Calculate the percentage of death penalties for cases where the race of the victim was white, and the percentage where the race of the victim was black.

In 2001 the baseball player Barry Bonds hit a record 73 home runs. During that year, he was at bat 476 times. In 1986, Bond's first season, he hit 16 home runs out of 413 at bats. Calculate Bond's rate of home runs for the 2001 and 1986 seasons.

In the Sydney 2000 Olympics, Michael Johnson (United States) won the gold medal in the men's 400 meter event. Alvin Harrison (United States) won the silver medal, and Gregory Haughton (Jamaica) won the bronze. The times (in seconds) of the 8 finalists are listed below. Calculate the five-number summary for the men's 400 meter final. 43.84 $\quad$ 44.40 $\quad$ 44.70 $\quad$ 45.01 $\quad$ 45.14 $\quad$ 45.26 $\quad$ 45.42 $\quad$ 45.55

According to the CIRP Freshman Survey, UCLA's annual survey of the nation's entering students at four-year colleges and universities, conducted in 2010, female students were far less likely to report high levels of emotional health than male students (45.9 percent versus 59.1 percent), a 13.2 percentage-point difference. This difference was reported as statistically significant. The statistically significant difference between male and female students means that

Use the following information for questions: The result of an Internet poll was reported as evidence that most people believe the pledge of allegiance is constitutional. The poll was conducted by posting a notice on a website and asking people to respond. The results were based on 235 people who responded. Of the 235 people, 172 (73%) believed that the pledge is constitutional, while 63 (27%) believed that the pledge is unconstitutional. -The results of this poll

If a magazine sends a survey to a random sample of 10,000 of its subscribers but only 3000 of them return the survey, the sample results may not be representative of the population of subscribers because

The five numbers in a five-number summary are the

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. -What is the approximate margin of error for this survey? Did the story report the correct margin of error?

Student grade point averages (GPAs) are calculated by assigning a number to each letter grade earned, with A = 4, B = 3, C = 2, D = 1 and F = 0, then finding the average. A student proposes using the median of the numbers instead and calls this medGPA. A student has taken five courses (all an equal number of credit hours) and the grades were A, A, F, B, A. The usual GPA for these grades is 3.0. Should the student prefer using the median (medGPA)?

Drawn below are two dotplots displaying the number of minutes spent talking on the telephone during a typical week 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 result of an Internet poll was reported as evidence that most people believe the pledge of allegiance is constitutional. The poll was conducted by posting a notice on a website and asking people to respond. The results were based on 235 people who responded. Of the 235 people, 172 (73%) believed that the pledge is constitutional, while 63 (27%) believed that the pledge is unconstitutional. -Assuming the poll had been based on a random sample with a sample size of 235, the reported margin of error of 3%

Use the following information for questions: First-year college students' self-ratings of their emotional health dropped to record low levels in 2010, according to the CIRP Freshman Survey, UCLA's annual survey of the nation's entering students at four-year colleges and universities. The rate of students who reported that their emotional health was in the "highest 10 percent" or "above average" was 519 per 1000 student. This was a drop of 34 per 1000 students from 2009 and a significant decline from the rate of students who placed themselves in those categories when self-ratings of emotional health were first measured in 1985. -What was the rate of students who reported that their emotional health was in the "highest 10 percent" or "above average" in 2009?

In a poll of students in grades 6 through 12, 13% reported that someone had seriously threatened to shoot them in the past year. This percentage was based on a sample of 2,508 students in 96 schools for which the principal had to give consent before the students could be surveyed. Give one possible explanation of why the sample may not have been representative of the population of all students in grades 6 through 12.

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 an excellent rating to their high schools.

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 strokes for women in the HRT group was 41% higher than the rate of strokes for women in the placebo group. The baseline rate of strokes in the placebo group was 21 per 10,000 women. What was the rate of strokes in the HRT group?

A news article with the headline "Arming commercial pilots" reported that 50% of first class and business travelers believe that pilots should be armed as an additional security measure, while 50% believed that pilots should not be armed. The results of the study

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. -Provide an interval of numbers that is 95% certain to cover the true percentage of Americans who supported the bill in 2010.

In a study of advanced colorectal cancer, 100 patients were randomly assigned to receive either a high dose of Vitamin C or placebo. The study concluded that Vitamin C was not effective in the treatment of advanced colorectal cancer because none of the patients with disease showed any improvement in the two groups. The cause and effect conclusion