24.9 Is astrology scientific? The University of Chicago’s General Social Survey (GSS) is the nation’s most important social science sample survey. The GSS asked a random sample of adults their opinion about whether astrology is very or sort of scientific or not at all scientific. Is belief that astrology is scientific related to amount of higher education? Here is a two-way table of counts for people in the sample who had three levels of higher education degrees:

Calculate percentages that describe the nature of the relationship between amount of higher education and opinion about whether astrology is very scientific or sort of scientific or not at all scientific. Give a brief summary in words.

24.10 Weight-lifting injuries. Resistance training is a popular form of conditioning aimed at enhancing sports performance and is widely used among high school, college, and professional athletes, although its use for younger athletes is controversial. A random sample of 4111 patients between the ages of 8 and 30 admitted to U.S. emergency rooms with the injury code “weight-lifting” was obtained. These injuries were classified as “accidental” if caused by dropped weight or improper equipment use. The patients were also classified into the four age categories 8 to 13, 14 to 18, 19 to 22, and 23 to 30 years. Here is a two-way table of the results:

Calculate percentages that describe the nature of the relationship between age and whether the weight-lifting injuries were accidental or not. Give a brief summary in words.

24.11 Smoking by students and their families. How are the smoking habits of students related to the smoking habits of their close family members? Here is a two-way table from a survey of male students in six secondary schools in Malaysia:

Write a brief answer to the question posed, including a comparison of selected percentages.

24.12 Smoking by parents of preschoolers. How are the smoking habits of parents of preschoolers related to the education of the father? Here is a two-way table from a survey of the parents of preschoolers in Greece:

Write a brief answer to the question posed, including a comparison of selected percentages.

24.13 Python eggs. How is the hatching of water python eggs influenced by the temperature of the snake’s nest? Researchers assigned newly laid eggs to one of three temperatures: hot, neutral (room temperature), or cold. Hot duplicates the extra warmth provided by the mother python, and cold duplicates the absence of the mother. Here are the data on the number of eggs and the number that hatched:

24.14 Firearm violence. Here are counts from a study of firearm violence reported by the Annual Review of Public Health in 2015. In particular, we will examine homicides and suicides and whether a firearm was involved.

24.15 Who earns academic degrees? How do women and men compare in the pursuit of academic degrees? The following table presents counts (in thousands), as projected by the National Center for Education Statistics, of degrees earned in 2015–2016 categorized by the level of the degree and the sex of the recipient.

24.16 Smokers rate their health. The University of Michigan Health and Retirement Study (HRS) surveys more than 22,000 Americans over the age of 50 every two years. A subsample of the HRS participated in a 2009 Internet-based survey that collected information on a number of topical areas, including health (physical and mental health behaviors), psychosocial items, economics (income, assets, expectations, and consumption), and retirement. Two of the questions asked were: “Would you say your health is excellent, very good, good, fair, or poor?” and “Do you smoke cigarettes now?” Here is the two-way table that summarizes the answers on these two questions:

Describe the differences between the distributions of health status for those who are and are not current smokers with percentages with a graph and in words.

24.17 Totals aren’t enough. Here are the row and column totals for a two-way table with two rows and two columns:

Find two different sets of counts , , , and for the body of the table that give these same totals. This shows that the relationship between two variables cannot be obtained from the two individual distributions of the variables.

24.18 Airline flight delays. Here are the numbers of flights on time and delayed for two airlines at five airports during a one-month period. Overall on-time percentages for each airline are often reported in the news. The airport that flights serve is a lurking variable that can make such reports misleading.

24.19 Bias in the jury pool? The New Zealand Department of Justice did a study of the composition of juries in court cases. Of interest was whether Maori, the indigenous people of New Zealand, were adequately represented in jury pools. Here are the results for two districts, Rotura and Nelson, in New Zealand (similar results were found in all districts):

24.20 Field goal shooting. Here are data on field goal shooting for two members of the Benedict College 2014–2015 men’s basketball team:

24.21 Smokers rate their health. Exercise 24.16 gives the responses of a survey of 4310 Americans to questions about their health and whether they currently smoke cigarettes.

24.22 Is astrology scientific? In Exercise 24.9, you described the relationship between belief that astrology is scientific and amount of higher education. Is the observed association between these variables statistically significant? To find out, proceed as follows.

24.23 Smoking by students and their families. In Exercise 24.11, you saw that there is an association between smoking by close family members and smoking by high school students. The students are more likely to smoke if a close family member smokes. We want to know whether this association is statistically significant.

24.24 Python eggs. Exercise 24.13 presents data on the hatching of python eggs at three different temperatures. Does temperature have a significant effect on hatching? Write a clear summary of your work and your conclusion.

24.25 Stress and heart attacks. You read a newspaper article that describes a study of whether stress management can help reduce heart attacks. The 107 subjects all had reduced blood flow to the heart and so were at risk of a heart attack. They were assigned at random to three groups. The article goes on to say:

One group took a four-month stress management program, another underwent a four-month exercise program, and the third received usual heart care from their personal physicians.

In the next three years, only three of the 33 people in the stress management group suffered “cardiac events,’’ defined as a fatal or non-fatal heart attack or a surgical procedure such as a bypass or angioplasty. In the same period, seven of the 34 people in the exercise group and 12 out of the 40 patients in usual care suffered such events.

24.26 Standards for child care. Do unregulated providers of child care in their homes follow different health and safety practices in different cities? A study looked at people who regularly provided care for someone else’s children in poor areas of three cities. The numbers who required medical releases from parents to allow medical care in an emergency were 42 of 73 providers in Newark, New Jersey, 29 of 101 in Camden, New Jersey, and 48 of 107 in South Chicago, Illinois.