Exam 1: Statistics Success Stories and Cautionary Tales

If the sample size for a poll increases from 100 people to 400 people, the margin of error

In 1936, George Gallup correctly predicted the winner of the presidential election to be Franklin Roosevelt. His prediction was based on a random sample of 50,000 people. What was the margin of error for Gallup's survey?

Use the following information for questions: According to statistics published by the Centers for Disease Control and Prevention in January of 2011, 25.8 million people, or 8.3% of the U.S. population, are affected by either type 1 or type 2 diabetes. -Based on the numbers published by the CDCP, roughly how many people lived in the U.S. in January of 2011?

Use the following information for questions: According to statistics published by the Centers for Disease Control and Prevention in January of 2011, 25.8 million people, or 8.3% of the U.S. population, are affected by either type 1 or type 2 diabetes. -Suppose these results are based on hospital records of 10,000 patients. Provide an interval of numbers that is 95% certain to cover the true percentage of Americans who are affected by either type 1 or type 2 diabetes.

Which of the statistical principles stated below is false?

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". -In 1994, what percentage of households consisted of a married couple with children?

Which of the following is true about the use of sample surveys?

"Does Prayer Lower Blood Pressure" was a question asked in Case Study 1.5. The moral of the story was

Drawn below are two dotplots displaying the number of letters that could be written in 15 seconds among 63 students using their dominant hand and then using their non-dominant hand. Also given are the 5 number summaries. Describe any differences or similarities between the two sets of data.

Over a 30-year period, the rate of the number of people killed by lightning compared to people killed by hurricanes was 350%. If the number of people killed by hurricanes was 16, what was the number of people killed by lightning? Is lightning a major cause of death?

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 shortest number of hours studied by anyone?

Use the following information for questions: Suppose you were to read about a study showing that people who sleep less than five hours a night have twice as much risk of a premature death as people who sleep seven or eight hours a night. -Can you conclude that sleeping the shorter hours causes a higher risk of premature death?

Use the following information for questions: A five number summary for hours studied in a week were 5, 12, 14, 18, and 20. -What is the value such that 25% or more of the students studied longer than that value?

In a National Cancer Institute study of the potential benefits of breast self-exams, 226,064 Chinese women in Shanghai were randomly assigned to a breast self-exam instruction group (132,979 women) or a control group (133,085 women). Over the next 10 to 11 years, there were 131 breast cancer deaths in the self-exam group, and 135 breast cancer deaths in the control group. The authors concluded that "intensive instruction in breast self-exam did not reduce mortality from breast cancer." What were the rates of breast cancer deaths in the two groups per 100,000 women?

An organization would like to conduct a survey of a sample of their membership to make conclusions about the entire membership. Given that they have a limited budget, they should focus their attention on

Use the following information for questions: A five number summary for hours studied in a week were 5, 12, 14, 18, and 20. -What is the value such that 50% or more of the students studied longer than that value?

Suppose a Gallup Poll using a sample of 400 individuals found that 25% of them supported a particular opinion. An interval that is 95% certain to contain the truth about the population percent who support that opinion is

To investigate how trans fat consumption might affect fertility, researchers analyzed data available from 18,555 healthy women who participated in the Nurses' Health Study between 1991 and 1999. All were married and trying to get pregnant. It was reported that for every 2 percent increase in the amount of calories a woman got from trans fats instead of carbohydrates, her risk of infertility increased by 73 percent. "Even though this was an observational study, a cause and affect relationship between the consumption of trans fat and fertility has been established because the increase in risk is significantly more than 50 percent."

To investigate how trans fat consumption might affect fertility, researchers analyzed data available from 18,555 healthy women who participated in the Nurses' Health Study between 1991 and 1999. All were married and trying to get pregnant. It was reported that for every 2 percent increase in the amount of calories a woman got from trans fats instead of carbohydrates, her risk of infertility increased by 73 percent. "The relationship between the consumption of trans fat and fertility may not be there at all, since it could all be affected by a confounding variable such as exercise or environmental variables."

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. -What are some confounding variables that might also explain the observed difference in percentages of death penalties for cases where the victim was white versus black?