The article “Display of health risk behaviors on MySpace by adolescents” (Archives of Pediatrics and Adolescent Medicine [2009]: 27–34) described a study in which researchers looked at a random sample of 500 publicly accessible MySpace web profiles posted by 18-year-olds. The content of each profile was analyzed. One of the conclusions reported was that displaying sport or hobby involvement was associated with decreased references to risky behavior (sexual references or references to substance abuse or violence). a. Is it reasonable to generalize the stated conclusion to all 18-year-olds with a publicly accessible MySpace web profile? What aspect of the study supports your answer? b. Not all MySpace users have a publicly accessible profile. Is it reasonable to generalize the stated conclusion to all 18-year-old MySpace users? Explain. c. Is it reasonable to generalize the stated conclusion to all MySpace users with a publicly accessible profile? Explain.
> An article on the cost of housing in California (San Luis Obispo Tribune, March 30, 2001) included the following statement: “In Northern California, people from the San Francisco Bay area pushed into the Central Valley, benefiting from home prices that d
> In a study of the relationship between TV viewing and eating habits, a sample of 548 ethnically diverse students from Massachusetts was followed over a 19-month period (Pediatrics [2003]: 1321–1326). For each additional hour of television viewed per day,
> Use the data given in Exercise 4.33 to construct two scatterplots—one of number of cell phone calls versus age and the other of number of text messages sent versus age. Based on the scatterplots, do you think age is a better predictor o
> Use the data given in the previous exercise to find the equation of the least squares regression line for predicting y = Number of text messages sent using x = Age as a predictor
> The following table gives data on age, number of cell phone calls made in a typical day, and number of text messages sent in a typical day for a random sample of 10 people selected from those enrolled in adult education classes offered by a school distri
> The report “airline Quality rating 2016” (www .airlinequalityrating.com/reports/2016_aQr_Final.pdf, retrieved april 22, 2017) included the accompanying data on the on-time arrival percentage and the number of complaint
> The California state Park system statistical report for the 2014/2015 Fiscal Year (www.parks.ca.gov/pages/795 /files/14-15%20statistical%20report%20-%20internet .pdf, retrieved april 22, 2017) gave the accompanying data on x = Amount of money collected i
> For the data in Exercise 3.22, subtract 10 from each sample observation. For the new set of values, calculate the mean and all the deviations from the mean. How do these deviations compare to the deviations from the mean for the original sample? How will
> The authors of the paper “evaluating existing Movement hypotheses in linear systems Using larval stream salamanders” (Canadian Journal of Zoology [2009]: 292–298) investigated whether water temperatur
> The accompanying data are a subset of data from the report “great jobs, great lives” (gallup-Purdue index 2015 report, www.gallup.com/reports/197144/gallup-purdue -index-report-2015.aspx, retrieved april 22, 2017). The
> What does it mean when we say that the regression line is the least squares regression line?
> Two scatterplots follow. Explain why it makes sense to use the least squares regression line to summarize the relationship between x and y for one of these data sets but not the other. Scatterplot 1 Scatterplot 2 110 100 90 + 80 y 70 60 50 + 40 + 3
> The authors of the paper “statistical Methods for assessing agreement between two Methods of Clinical Measurement” (International Journal of Nursing Studies [2010]: 931–936) compared two different ins
> Acrylamide is a chemical that is sometimes found in cooked starchy foods and which is thought to increase the risk of certain kinds of cancer. The paper “a statistical regression Model for the estimation of acrylamide Concentrations in
> Medical researchers have noted that adolescent females are much more likely to deliver lowbirth-weight babies than are adult females. Because low-birth-weight babies have a higher mortality rate, a number of studies have examined the relationship between
> Data on x = Size of a house (in square feet) and y = Amount of natural gas used (therms) during a specified period were used to fit the least squares regression line. The slope was 0.017 and the intercept was -5.0. Houses in this data set ranged in size
> Data on y = Time to complete a task (in minutes) and x = Number of hours of sleep on the previous night were used to find the least squares regression line. The equation of the line was ˆ y = 12 - 0.36x. For this data set, would the sum of squa
> Two scatterplots are shown below. Explain why it makes sense to use the least squares regression line to summarize the relationship between x and y for one of these data sets but not the other. Scatterplot 1 Scatterplot 2 110 100 90 80 y 70 60 + 5
> Although bats are not known for their eyesight, they are able to locate prey (mainly insects) by emitting high-pitched sounds and listening for echoes. A paper appearing in Animal Behaviour (“the echolocation of Flying insects by bats” [1960]: 141–154) g
> It may seem odd, but biologists can tell how old a lobster is by measuring the concentration of pigment in the lobster’s eye. The authors of the paper “neurolipofuscin is a Measure of age in Panulirus argus, the Caribb
> A sample of automobiles traveling on a particular segment of a highway is selected. Each one travels at roughly a constant rate of speed, although speed does vary from auto to auto. Let x = Speed and y = Time needed to travel this segment. Would the samp
> An auction house released a list of 25 recently sold paintings. The artist’s name and the sale price of each painting appear on the list. Would the correlation coefficient be an appropriate way to summarize the relationship between artist and sale price?
> Below are the data used to construct the time series plots in the previous exercise. Calculate the value of the correlation coefficient for the amount spent on science, space, and technology and the amount spent on pets. Explain how this value is consist
> The amount of money spent each year on science, space, and technology in the United States (in millions of dollars) and the amount of money spent on pets in the United States (in billions of dollars) for the years 2000 to 2009 were used to construct the
> Each year the Harris Poll surveys Americans on a number of issues. It uses responses to several questions to calculate a “Happiness” index that measures overall happiness. The article “latest happines
> The paper “religiosity and teen birth rate in the United states” (Reproductive Health [2009]: 14–20) included data on teen birth rate and on a measure of conservative religious beliefs for each of 49
> Data from the U.s. Federal reserve board (www .federalreserve.gov/releases/housedebt/, retrieved april 21, 2017) on consumer debt (as a percentage of personal income) and mortgage debt (also as a percentage of personal income) for the 10 years from 2006
> Draw two scatterplots, one for which r = 1 and a second for which r = -1.
> The paper “Digit ratio as an indicator of numeracy relative to literacy in 7-Year-old british schoolchildren” (British Journal of Psychology [2008]: 75–85) investigated a possible relationship between x = Digit ratio (the ratio of the length of the secon
> Acrylamide, a possible cancer-causing substance, forms in high-carbohydrate foods cooked at high temperatures. Acrylamide levels can vary widely even within the same type of food. An article appearing in the journal Food Chemistry (March 2014, 204–211) i
> For each of the following pairs of variables, indicate whether you would expect a positive correlation, a negative correlation, or a correlation close to 0. Explain your choice. a. Weight of a car and gas mileage b. Size and selling price of a house c
> For each of the scatterplots shown, answer the following questions: i. Does there appear to be a relationship between x and y? ii. If so, does the relationship appear to be linear? iii. I f so, would you describe the linear relationship as positive or
> The paper “noncognitive Predictors of student athletes’ academic Performance” (Journal of College Reading and Learning [2000]: e167) summarizes a study of 200 Division I athletes. It was reported that the correlation coefficient for college grade point a
> The article “that’s rich: More You Drink, More You earn” (Calgary Herald, april 16, 2002) reported that there was a positive correlation between alcohol consumption and income. Is it reasonable to conclude that increasing alcohol consumption will increas
> Is the following statement correct? Explain why or why not. A correlation coefficient of 0 implies that there is no relationship between two variables.
> Each year, marketing firm j.D. Power and associates surveys new car owners 90 days after they purchase their cars. These data are used to rate auto brands (Toyota, Ford, etc.) on quality and customer satisfaction. Data for 2015 on a quality rating (numbe
> The article “$115K! the 13 best Paying U.s. Companies” (USA TODAY, august 11, 2015) gave the following data on median worker pay (in thousands of dollars) and the 1-year percent change in stock price for the 13 highest
> The paper “the relationship between Cell Phone Use, academic Performance, anxiety, and satisfaction with life in College students” (Computers in Human Behavior [2014]: 343–350) described a study of cell phone use among undergraduate college students at a
> For each of the following pairs of variables, indicate whether you would expect a positive correlation, a negative correlation, or a correlation close to 0. Explain your choice. a. Interest rate and number of loan applications b. Height and IQ c. Heig
> For each of the scatterplots shown, answer the following questions: i. Does there appear to be a relationship between x and y? ii. If so, does the relationship appear to be linear? iii. If so, would you describe the linear relationship as positive or
> The article “caffeinated energy Drinks—a growing Problem” (Drug and Alcohol Dependence [2009]: 1–10) gave the accompanying data (on the next page) on caffeine concentration (mg/ounce
> To learn about the reason parents believe their child is heavier than the recommended weight for children of the same age, each person in a sample of parents of overweight children was asked what they thought was the most important contributing factor. P
> For the following numerical variables, state whether each is discrete or continuous. a. The number of insufficient-funds checks received by a grocery store during a given month b. The amount by which a 1-pound package of ground beef decreases in weight
> Classify each of the following variables as either categorical or numerical. For those that are numerical, determine whether they are discrete or continuous. a. Number of students in a class of 35 who turn in a term paper before the due date b. G ender
> The article “rethinking calcium Supplements” (U.S. Airways Magazine, October 2010) describes a study investigating whether taking calcium supplements increases the risk of heart attack. Two hundred people were randomly selected from a list of all people
> The article “rethinking calcium Supplements” (U.S. Airways Magazine, October 2010) describes a study investigating whether taking calcium supplements increases the risk of heart attack. Two hundred people were randomly selected from a list of all people
> The article “rethinking calcium Supplements” (U.S. Airways Magazine, October 2010) describes a study investigating whether taking calcium supplements increases the risk of heart attack. Every heart attack patient and every patient admitted for an illness
> To examine the effect of exercise on body composition, healthy women aged 35 to 50 were classified as either active (nine or more hours of physical activity per week) or sedentary (“effects of habitual Physical activity on the resting Metabolic rates and
> The authors of the paper “Popular video games: Quantifying the Presentation of violence and its context” (Journal of Broadcasting & Electronic Media [2003]: 58–76) investigated the relationship between video game rating—suitable for everyone (E), suitabl
> Morningstar is an investment research firm that publishes some online educational materials. The materials for an online course called “looking at historical risk” (news.morningstar.com/classroom2/course .asp?docid =2927&page=2&cn=com, retrieved august 3
> Can moving their hands help children learn math? This is the question investigated by the authors of the paper “gesturing gives children new ideas about Math” (Psychological Science [2009]: 267–272). An experiment was conducted to compare two different m
> According to the article “rubbing hands together Under warm air Dryers can counteract bacteria reduction” (Infectious Disease News, September 22, 2010), washing your hands isn’t enough—good “hand hygiene” also includes drying hands thoroughly. The articl
> The article “Super bowls: Serving bowl Size and Food consumption” (Journal of the American Medical Association [2005]: 1727–1728) describes an experiment investigating how the size of serving bowls influences the amount a person eats. In this experiment,
> The article “Yes that Miley cyrus biography helps learning” (The Globe and Mail, august 5, 2010) describes an experiment investigating whether providing summer reading books to low-income children would affect school performance. Subjects in the experime
> In many digital environments, users are allowed to choose how they are represented visually online. Does the way in which people are represented online affect online behavior? This question was examined by the authors of the paper “the Proteus effect: th
> A petition with 500 signatures is submitted to a college’s student council. The council president would like to determine what proportion of those who signed the petition are actually registered students at the college. There is not enough time to check
> According to the article “effect of Preparation Methods on total Fat content, Moisture content, and Sensory characteristics of breaded chicken nuggets and beef Steak Fingers” (Family and Consumer Sciences Research Journal [1999]: 18–27), sensory tests we
> For each of the following statements, identify the number that appears in boldface type as the value of either a population characteristic or a statistic: a. A department store reports that 84% of all customers who use the store’s credit plan pay their
> The student senate at a college with 15,000 students is interested in the proportion of students who favor a change in the grading system to allow for plus and minus grades (for example, B+, B, B-, rather than just B). Two hundred students are interviewe
> The accompanying data are a subset of data read from a graph in the paper “ladies First? a Field Study of Discrimination in coffee Shops” (Applied Economics [april, 2008]). The data are the waiting times (in seconds) b
> For each of the following, determine whether the statistical study described is an observational study or an experiment. Give a brief explanation of your choice. a. Can choosing the right music make wine taste better? This question was investigated by a
> The paper “turning to learn: Screen orientation and reasoning from Small Devices” (Computers in Human Behavior [2011]: 793–797) describes a study that investigated whether cell phones with small scree
> Does living in the South cause high blood pressure? Data from a group of 6278 people questioned in the Third National Health and Nutritional Examination Survey between 1988 and 1994 indicate that a greater percentage of Southerners have high blood pressu
> An article titled “guard Your Kids against allergies: get them a Pet” (San Luis Obispo Tribune, august 28, 2002) described a study that led researchers to conclude that “babies raised with two or more animals are about half as likely to have allergies by
> “Strengthen Your Marriage with Prayer” is a headline that appeared in the magazine Woman’s World (November 1, 2010). The article went on to state that couples who attend religious services and pray together have happier, stronger marriages than those who
> “Strengthen Your Marriage with Prayer” is a headline that appeared in the magazine Woman’s World (November 1, 2010). The article went on to state that couples who attend religious services and pray together have happier, stronger marriages than those who
> “Strengthen Your Marriage with Prayer” is a headline that appeared in the magazine Woman’s World (November 1, 2010). The article went on to state that couples who attend religious services and pray together have happier, stronger marriages than those who
> The paper “effect of cell Phone Distraction on Pediatric Pedestrian injury risk” (Pediatrics [2009]: e179–e185) describes an experiment examining whether people talking on a cell phone are at greater risk of an accident when crossing the street than when
> Researchers at the University of Utah carried out a study to see if the size of the fork used to eat dinner has an effect on how much food is consumed (Food Network Magazine, January 2012). The researchers assigned people to one of two groups. One group
> A survey of affluent Americans (those with incomes of $75,000 or more) indicated that 57% would rather have more time than more money (USA TODAY, january 29, 2003). a. What condition on how the data were collected would make it reasonable to generalize t
> Cost per serving (in cents) for 15 high-fiber cereals rated very good or good by Consumer Reports are shown below. Calculate and interpret the mean and standard deviation for this data set. 46 49 62 41 19 77 71 30 53 53 67 43 48 28 54
> One hundred students were selected at random from those enrolled at a large college. Each of the selected students was asked to participate in a study, and all agreed to participate. For each student, a coin was tossed. If the coin landed heads up, the s
> Two hundred people volunteered to participate in a statistical study. For each volunteer, a coin was tossed. If the coin landed heads up, the volunteer was assigned to group 1. If the coin landed tails up, the volunteer was assigned to group 2. Those in
> Two hundred people volunteered to participate in a statistical study. Each person was asked how often he or she ate pecans, and their cholesterol levels were also measured. The average cholesterol level for those who ate pecans more than once a week was
> One hundred people who live in Los Angeles volunteered to participate in a statistical study. The volunteers were divided based on gender, with women in group 1 and men in group 2. Those in group 1 were asked to eat 3 ounces of pecans daily for 1 month.
> Five hundred students were selected at random from those enrolled at a large college in Florida. Each student in the sample was asked whether they ate pecans more than once in a typical week, and their cholesterol levels were also measured. The average c
> The following is from an article titled “after the workout, got chocolate Milk?” that appeared in the Chicago Tribune (January 18, 2005): Researchers at Indiana University at Bloomington have found that chocolate milk effectively helps athletes recover
> The article “heartfelt thanks to Fido” (San Luis Obispo Tribune, july 5, 2003) summarized a study that appeared in the American Journal of Cardiology (March 15, 2003). In this study, researchers measured heart rate variability (a measure of the heart’s a
> A study described in Food Network Magazine (January 2012) concluded that people who push a shopping cart at a grocery store are less likely to purchase junk food than those who use a hand-held basket. a. Do you think this study was an observational stud
> Pismo Beach, California, has an annual clam festival that includes a clam chowder contest. Judges rate clam chowders from local restaurants. The judges are not aware of which chowder is from which restaurant when they assign the ratings. One year, much t
> In an experiment comparing two different surgical procedures for hernia repair (“a Single-blinded, randomized comparison of laparoscopic versus open hernia repair in children,” Pediatrics [2009]: 332–
> The U.S. Department of Transportation reported the number of speed-related crash fatalities for the 15 states that had the highest number of these fatalities in 2012 (2012 Speeding Traffic Safety Facts, May 2014). a. Calculate and interpret the mean and
> Could the experiment described above have been double-blind? Explain why or why not.
> Explain why it is important that the surgeons be assigned at random to the two music conditions in the experiment described above.
> Explain why it is important to control each of the following variables in the experiment described above. a. the type of surgery performed b. operating room temperature c. volume at which the music was played
> What are the experimental conditions for the experiment described above? What is the response variable?
> An advertisement for a sweatshirt that appeared in SkyMall Magazine (a catalog distributed by some airlines) stated the following: This is not your ordinary hoody! Why? Fact: Research shows that written words on containers of water can influence the wat
> Suppose that you would like to know if keyboard design has an effect on wrist angle, as shown in the accompanying figure. You have 40 volunteers who have agreed to participate in an experiment to compare two different keyboards. Describe the steps in a
> The article “Doctor Dogs Diagnose cancer by Sniffing it out” (Knight Ridder Newspapers, January 9, 2006) refers to an experiment described in the journal Integrative Cancer Therapies. In this experiment, dogs were trained to distinguish between people wi
> The article “Study Points to benefits of Knee replacement Surgery over therapy alone” (New York Times, October 21, 2015) describes a study to compare two treatments for people with knee pain. In the study, 50 people with arthritis received knee replaceme
> The Institute of Psychiatry at Kings College London found that dealing with “infomania” has a temporary, but significant, negative effect on IQ (Discover, november 2005). To reach this conclusion, researchers divided volunteers into two groups. Each subj
> The paper “effect of a nutritional Supplement on hair loss in women” (Journal of Cosmetic Dermatology [2015]: 76–82) describes an experiment to see if a dietary supplement consisting of Omega 3, Omega 6, and antioxidants could reduce hair loss in women w
> A study of college students showed a temporary gain of up to nine IQ points after listening to a Mozart piano sonata. This result, dubbed the Mozart effect, has since been criticized by a number of researchers who have been unable to confirm the result i
> In an experiment to compare two different surgical procedures for hernia repair (“a Single-blinded, randomized comparison of laparoscopic versus open hernia repair in children,” Pediatrics [2009]: 332–336), 89 children were assigned at random to one of t
> In an experiment to assess the effect of wearing compression socks during a marathon, 20 runners in the 2013 Hartford Marathon were randomly assigned to two groups ("compression and clots in athletes who travel," Lower Extremities Review, lermagazine.com
> Does playing action video games provide more than just entertainment? The authors of the paper “action-videogame experience alters the Spatial resolution of vision” (Psychological Science [2007]: 88–94) concluded that spatial resolution, an important asp
> Whether or not to continue a Mardi Gras Parade through downtown San Luis Obispo, California, is a hotly debated topic. The parade is popular with students and many residents, but some celebrations have led to complaints and a call to eliminate the parade
> In 2000, the chairman of a California ballot initiative campaign to add “none of the above” to the list of ballot options in all candidate races was quite critical of a Field poll that showed his measure trailing by 10 percentage points. The poll was bas
> A building contractor has a chance to buy an odd lot of 5000 used bricks at an auction. She is interested in determining the proportion of bricks in the lot that are cracked and therefore unusable for her current project, but she does not have enough tim
> The supervisors of a rural county are interested in the proportion of property owners who support the construction of a sewer system. Because it is too costly to contact all 7000 property owners, a survey of 500 owners (selected at random) is undertaken.
