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Seven of the ten largest cities in the world are in the Eastern Hemisphere (including the largest: Tokyo, Japan) and three are in the Western Hemisphere. \(^{11}\) Table 1.4 shows the populations, in millions of people, for these cities. (a) How many cases are there in this dataset? How many variables are there and what are they? Is each categorical or quantitative? (b) Display the information in Table 1.4 as a dataset with cases as rows and variables as columns. $$ \begin{array}{ll} \hline \text { Eastern hemisphere: } & 37,26,23,22,21,21,21 \\ \text { Western hemisphere: } & 21,20,19 \\ \hline \end{array} $$

Can experiences of parents affect future children? New studies \(^{12}\) suggest that they can: Early life experiences of parents appear to cause permanent changes in sperm and eggs. In one study, some male rats were fed a high-fat diet with \(43 \%\) of calories from fat (a typical American diet), while others were fed a normal healthy rat diet. Not surprisingly, the rats fed the high- fat diet were far more likely than the normal-diet rats to develop metabolic syndrome (characterized by such things as excess weight, excess fat, insulin resistance, and glucose intolerance.) What surprised the scientists was that the daughters of these rats were also far more likely to develop metabolic syndrome than the daughters of rats fed healthy diets. None of the daughters and none of the mothers ate a high-fat diet and the fathers did not have any contact with the daughters. The high-fat diet of the fathers appeared to cause negative effects for their daughters. What are the two main variables in this study? Is each categorical or quantitative? Identify the explanatory and response variables.

In Exercise \(1.18,\) we ask whether experiences of parents can affect future children, and describe a study that suggests the answer is yes. A second study, described in the same reference, shows similar effects. Young female mice were assigned to either live for two weeks in an enriched environment or not. Matching what has been seen in other similar experiments, the adult mice who had been exposed to an enriched environment were smarter (in the sense that they learned how to navigate mazes faster) than the mice that did not have that experience. The other interesting result, however, was that the offspring of the mice exposed to the enriched environment were also smarter than the offspring of the other mice, even though none of the offspring were exposed to an enriched environment themselves. What are the two main variables in this study? Is each categorical or quantitative? Identify explanatory and response variables.

Hookahs are waterpipes used for smoking flavored tobacco. One study \({ }^{13}\) of 3770 university students in North Carolina found that \(40 \%\) had smoked a hookah at least once, with many claiming that the hookah smoke is safer than cigarette smoke. However, a second study observed people at a hookah bar and recorded the length of the session, the frequency of puffing, and the depth of inhalation. An average session lasted one hour and the smoke inhaled from an average session was equal to the smoke in more than 100 cigarettes. Finally, a third study measured the amount of tar, nicotine, and heavy metals in samples of hookah smoke, finding that the water in a hookah filters out only a very small percentage of these chemicals. Based on these studies and others, many states are introducing laws to ban or limit hookah bars. In each of the three studies, identify the individual cases, the variables, and whether each variable is quantitative or categorical.

Next time you see an elderly man, check out his nose and ears! While most parts of the human body stop growing as we reach adulthood, studies show that noses and ears continue to grow larger throughout our lifetime. In one study \(^{14}\) examining noses, researchers report "Age significantly influenced all analyzed measurements:" including volume, surface area, height, and width of noses. The gender of the 859 participants in the study was also recorded, and the study reports that "male increments in nasal dimensions were larger than female ones." (a) How many variables are mentioned in this description? (b) How many of the variables are categorical? How many are quantitative? (c) If we create a dataset of the information with cases as rows and variables as columns, how many rows and how many columns would the dataset have?

For the 2015 Intel Science Fair, two brothers in high school recruited 47 of their classmates to take part in a two-stage study. Participants had to read two different passages and then answer questions on them, and each person's score was recorded for each of the two tests. There were no distractions for one of the passages, but participants received text messages while they read the other passage. Participants scored significantly worse when distracted by incoming texts. Participants were also asked if they thought they were good at multitasking (yes or no) but "even students who were confident of their abilities did just as poorly on the test while texting." 15 (a) What are the cases? (b) What are the variables? Is each variable categorical or quantitative? (c) If we create a dataset of the information with cases as rows and variables as columns, how many rows and how many columns would the dataset have?

How Are Age and Income Related? An economist collects data from many people to determine how age and income are related. How the data is collected determines whether the variables are quantitative or categorical. Describe how the information might be recorded if we regard both variables as quantitative. Then describe a different way to record information about these two variables that would make the variables categorical.

State whether the data are best described as a population or a sample. A questionnaire to understand athletic participation on a college campus is emailed to 50 college students, and all of them respond.

In Exercises 1.32 to \(1.35,\) describe the sample and describe a reasonable population. A sociologist conducting a survey at a mall interviews 120 people about their cell phone use.

Describe the sample and describe a reasonable population. A cell phone carrier sends a satisfaction survey to 100 randomly selected customers.