Stats Exam 1
The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. According to the standard deviation rule, almost 2.5% of the students spent more than what amount of money on textbooks in a semester? -$195 -$215 -$275 -$295
$275
A survey was conducted to determine the number of servings of vegetables eaten, per day, by adolescents in the United States. The following table shows the results: What is the modal number of vegetable servings eaten, per day, by adolescents in the United States? -0 -1 -2 -3 -More than 3
2
A study is conducted to determine the effect of television violence on men. A random sample of 500 men was selected and a survey administered to determine if the men watched high or low levels of TV violence as children and if they were physically abusive (hit, grabbed, or shoved) towards their partners as adults. Which of the following would be a meaningful display of the data from this study? -Side-by-side boxplots -A pie chart -A histogram -A scatterplot -A two-way table
A two-way table
Ross Times, the student newspaper of Ross College, printed a "What do you think?" column feature asking: "Do you think that the college is doing enough to provide student parking?" Anyone could mail in a response or use the paper's Web site to respond. In all, 126 answers were received. This is an example of what type of sample? -A simple random sample -A voluntary response sample -A convenience sample -A multistage sample
A voluntary response sample
Talkshow host "Bull" Loney asked listeners of his to call in to give their opinion on a topic that he had just spent most of his program ranting about. The station got 384 calls. This is an example of what type of sample? -A multistage sample -A convenience sample -A simple random sample -A voluntary response sample
A voluntary response sample
The boxplots below show the number of marshmallows in a bag, as estimated by students in two elementary school classes. Which class has greater variability in students' estimate of the number of marshmallows? -Ms. Apple's class -Ms. Banana's class -Both classes have the same variability in students' estimates. -It is impossible to tell from the boxplots.
Ms. Apple's class
The boxplots below show the number of marshmallows in a bag, as estimated by students in two elementary school classes. Which class has a greater percentage of estimates between 50 and 100 marshmallows? -Ms. Apple's class -Ms. Banana's class -Both classes have the same percentage of estimates between 50 and 100. -It is impossible to tell from the boxplots.
Ms. Banana's class
The boxplots below show the number of marshmallows in a bag, as estimated by students in two elementary school classes. Which class has the greater percentage of estimates over 100? -Ms. Apple's class -Ms. Banana's class -Both classes have the same percentage of estimates over 100. -It is impossible to tell from the boxplots.
Ms. Banana's class
A student survey was conducted at a major university, and data were collected from a random sample of 750 undergraduate students. One variable that was recorded for each student was the student's answer to the question: "What region of the country did you live in just prior to enrolling in this university? Northeast/Southeast/Northwest/Southwest/Midwest/Outside the U.S." These data would be best displayed using which of the following? -Boxplot -Histogram -Stemplot -IQR -Pie chart
Pie chart
Thirty adults were asked which of the following conveniences they would find most difficult to do without: television, refrigerator, air conditioning, public transportation, or microwave. These data would be best displayed using which of the following? -Boxplot -Stemplot -IQR -Histogram -Pie chart
Pie chart
A correlation of r = 0.85 is found between weekly sales of firewood and cough drops over a 1-year period. Which of the following is a correct interpretation of this correlation value? -Fire must be the cause of coughing. -There is a pretty strong positive linear relationship between sales of firewood and cough drops. -Temperature is a possible lurking variable that is behind this relationship.
Temperature is a possible lurking variable that is behind this relationship.
The histogram below displays the distribution of 50 ages at death due to trauma (accidents and homicides) that were observed in a certain hospital during a week. For the data described by the above histogram, which of the following is a correct statement about the median? -The median will be bigger than the mean. -The median will be smaller than the mean. -The median and the mean will be about the same. -The median and the range will be about the same.
The median will be smaller than the mean.
This histogram shows the times, in minutes, required for 25 rats in an animal behavior experiment to successfully navigate a maze. For the data described by the above histogram, which of the following is a correct statement about the median? -The median will be smaller than the mean. -The median will be larger than the mean. -The median and the mean will be about the same. -The median and the range will be about the same.
The median will be smaller than the mean.
Students in a large statistics class were randomly divided into two groups. The first group took the midterm exam with soft music playing in the background, and the second group took the exam with no music playing. After the exam was completed, a researcher compared deidentified exam scores of the two groups. Which of the following is the reason this experiment was not blind? -Students were randomized into the two groups. -The students knew whether or not music was playing while they were taking the exam. -Researchers looked at exam scores for the two groups. -The sample sizes in both groups was large. -Some of the students may not have studied for the exam.
The students knew whether or not music was playing while they were taking the exam.
Which one of the following is an advantage of an observational study when compared to an experimental study? -Lurking variables are not a problem. -The treatment can be controlled by the researchers. -The treatments studied may be unethical when used in experiments. -Randomization is less important because researchers are observing things "as they happen."
The treatments studied may be unethical when used in experiments.
The following data, on the number of children born per 1,000 women, is from the Current Population Reports—Fertility of American Women: 2008: Number of Children 0 1 2 3 4 5 or more Frequency 45.7% 17.0% 21.1% 10.6% 3.9% 1.8% What is the modal number of children born to American women in 2008? -0 -1 -2 -3
0
Which of the following valid probabilities represents an event that is impossible? -−1 -0 -0.0001 -1
0.0001
Which of the following probabilities could describe an event that is likely but not certain? -0.2 -0.5 -0.8 -1
0.8
Research Question: What is the combined effect of fertilizer and watering on cherry tomato plants? Planters were built that each contained 10 cherry tomato plants. Each planter was identical except that it received a different treatment of water and fertilizer than the other planters. Treatments consisted of a combination of one of four watering schedules and one of three fertilizer concentrations. The plants were tended according to these treatments, and after 65 days, the average number and weight of the tomatoes per plant were measured for each treatment group. How many different groups are there altogether in this study? -3 -4 -7 -12
12
The distribution of the IQ (Intelligence Quotient) is approximately normal in shape with a mean of 100 and a standard deviation of 15. According to the standard deviation rule, only 0.15% of people have an IQ over what score? -55 -100 -115 -130 -145
145
Which of the following best describes the method of randomized response? -A method in which subjects answer the questions in a survey in a random order -A technique used to minimize the bias in the responses of subjects to sensitive questions -A method in which subjects answer each of the questions in a survey with a random guess -A sampling method
A technique used to minimize the bias in the responses of subjects to sensitive questions
This histogram shows the times, in minutes, required for 25 rats in an animal behavior experiment to successfully navigate a maze. Which of the following is a possible value of the median in this example? -3.3 -3.9 -4.6 -5.5
3.9
An urn contains 22 marbles consisting of 10 red marbles, 7 blue marbles, and 5 yellow marbles. What is the probability of randomly selecting a blue marble from the urn? Some answers have been rounded to the nearest percentage. -7% -22% -32% -50%
32%
The histogram below displays the distribution of 50 ages at death due to trauma (accidents and homicides) that occurred in a certain hospital during a week. Which of the following is a possible value of the median in this example? -23 -45 -50 -33
33
A 2009 study analyzed data from the National Longitudinal Study of Adolescent Health. Participants were followed into adulthood. Each study participant was categorized as to whether they were obese (BMI >30) or not and whether they were dating, cohabiting, or married. The table below summarizes the results. What percentage of those who were married were obese? (Round your answer to 1 decimal place.) -44.4% (147/331) -34.7% (147/424) -32.8% (424/1293) -25.6% (331/1293)
34.7% (147/424)
Based on the results of a nationwide study, the number of contacts programmed into cell phones are summarized on the following boxplot: Which interval contains the greatest amount of data? -0-50 -50-100 -75-125 -125-175 -It is impossible to tell.
50-100
Research Question: What is the combined effect of medication and diet on blood pressure in adult males? A randomized, controlled experiment investigated this question using a random sample of 540 adult males as subjects. At the beginning of the study, researchers measured the blood pressure of all the subjects. Each subject was given a month's supply of either Drug A, Drug B, or a placebo, then was assigned to be on either a low-fat diet or a low-salt diet for that month-long period. At the end of the month, the researchers measured the blood pressure of each subject again, and compared the two blood pressure readings. How many different groups are there altogether in this study? -2 -3 -4 -5 -6
6
Here are the number of hours that 9 students spend on the computer on a typical day: 1 6 7 6 8 11 6 12 15 Which of the following represents the mode number of hours spent on the computer? -6.0 -7.0 -7.5 -8.0
6.0
The histogram below displays the distribution of 50 ages at death due to trauma (accidents and homicides) that were observed in a certain hospital during a week. What percentage of deaths were individuals younger than 35? -34% -60% -68% -70% -80%
68%
Here are the number of hours that 9 students spend on the computer on a typical day: 1 6 7 6 8 11 6 12 15 Which of the following represents the median number of hours spent on the computer? -6.0 -7.0 -7.5 -8.0
7.0
Here are the number of hours that 9 students spend on the computer on a typical day: 1 6 7 6 8 11 6 12 15 Which of the following represents the mean number of hours spent on the computer? -6.0 -7.0 -8.0 -9.0
8.0
This histogram shows the times, in minutes, required for 25 rats in an animal behavior experiment to successfully navigate a maze. What percentage of the rats navigated the maze in less than 5.5 minutes? -21% -60% -68% -70% -84%
84%
In a large lecture hall, students were handed a drawing of a woman. Students didn't know that those on the left side of the center aisle received a drawing of a young woman while those on the right side of the aisle were given a drawing of an old woman. A slide was then projected with an drawing that was an ambiguous combination of the two handouts and students were asked a series of questions. This is an example of which of the following? -A blind observational study -An observational study that isn't blind -A blind experiment -An experiment that isn't blind
A blind experiment
In an experiment to see if aspirin reduces the chance of having a heart attack, which of the following would be a placebo? -The place where the subjects go when they have a heart attack -A dummy pill that looks like aspirin but has no active ingredients -The sampling method -A procedure for deciding who gets the aspirin treatment -The randomization procedure
A dummy pill that looks like aspirin but has no active ingredients
Which of the following is an example of stratified sampling? -A health educator wanted to study the sleeping habits of the undergraduate students in her university. For her study, the researcher chose a simple random sample of size 150 from each of the classes (150 freshmen, 150 sophomores, 150 juniors, and 150 seniors) for a total of 600 sampled students. -The human resources department of a large bank wanted to assess the job satisfaction of the bank's workers. The department chose four of the bank's branches at random and used all of the workers in those four branches as the subjects for the study. -A sample of 351 people called a radio show to express their opinions about the verdict in a murder trial. In order to assess students' satisfaction with the food establishment on campus, the first 50 students who came out of the student center were interviewed. -A poll asked a random sample of 1,112 adults whether they believe that the use of marijuana for medical reasons should be legalized.
A health educator wanted to study the sleeping habits of the undergraduate students in her university. For her study, the researcher chose a simple random sample of size 150 from each of the classes (150 freshmen, 150 sophomores, 150 juniors, and 150 seniors) for a total of 600 sampled students.
A survey was conducted to study the relationship between the annual income of a family and the amount of money the family spends on entertainment. Data were collected from a random sample of 280 families from a certain metropolitan area. Which of the following would be a meaningful display of the data from this study? -A scatterplot -A histogram -A two-way table -Side-by-side boxplots -A pie chart
A scatterplot
The faculty senate at a large university wanted to know what proportion of the students thought foreign language classes should be required for everyone. The statistics department offered to cooperate in conducting a survey, and a simple random sample of 500 students was selected from all the students enrolled in statistics classes. A survey form was sent by email to these 500 students. In this case, which of the following is the population of interest? -The students who responded to the email survey -All students who think that foreign language classes should be required for everyone -The 500 students who got the email survey -All students enrolled in a statistics class -All students at the university
All students at the university
The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. According to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester? -Between $215 and $255 -Between $195 and $275 -Between $175 and $295 -Less than $215 or more than $255 -Above $235
Between $175 and $295
The distribution of the IQ (Intelligence Quotient) is approximately normal in shape with a mean of 100 and a standard deviation of 15. According to the standard deviation rule, what range of IQ scores do many (68%) people have? -Between 85 and 115 -Between 70 and 130 -Between 55 and 145 -Less than 85 or more than 115 -Above 100
Between 85 and 115
The boxplots below show the real estate values of single-family homes in two neighboring cities (in thousands of dollars). Which city has greater variability in real estate values? -Tinytown -BigBurg -Both cities have the same variability in real estate values. -It is impossible to tell from the boxplots.
BigBurg
It is impossible to tell from the boxplots. The boxplots below show the real estate values of single-family homes in two neighboring cities (in thousands of dollars). Which city has the greater percentage of households with real estate values above $85,000? -Tinytown -Bigburg -Both cities have the same percentage of households with real estate values above $85,000. -It is impossible to tell from the boxplots.
Both cities have the same percentage of households with real estate values above $85,000.
A study seeks to answer the question, "Does Vitamin C level in the breast milk of new mothers reduce the risk of allergies in their breastfed infants?" The study concluded that high levels of vitamin C (measured in milligrams) were associated with a 30 percent lower risk of allergies in the infants. In this scenario, "presence of allergies" is what type of variable? -Categorical OR Quantitative
Categorical
If there is no relationship (linear or otherwise) between two quantitative variables as observed on a scatterplot, the value of the correlation coefficient, r, is likely to be which of the following? -Closer to 1 -Closer to −1 -Closer to 0 -Either closer to −1 or 1
Closer to 0
High blood pressure is unhealthy. Here are the results of one of the studies that link high blood pressure to death from cardiovascular disease. The researchers classified a group of white males aged 35 to 64 as having low blood pressure or high blood pressure, then followed the subjects for 5 years. The following two-way table gives the results of the study: In this example, which of the following would be appropriate to calculate? -Conditional row percentages -Conditional column percentages -The correlation coefficient r -The five-number summary of both variables
Conditional column percentages
The faculty senate at a large university wanted to know what proportion of the students thought foreign language classes should be required for everyone. The statistics department offered to cooperate in conducting a survey, and a simple random sample of 500 students was selected from all the students enrolled in statistics classes. A survey form was sent by email to these 500 students. True or false? Since the sample is random, it is representative of the population of interest. -True -False
False
Research Question: What is the combined effect of fertilizer and watering on cherry tomato plants? Planters were built that each contained 10 cherry tomato plants. Each planter was identical except that it received a different treatment of water and fertilizer than the other planters. Treatments consisted of a combination of one of four watering schedules and one of three fertilizer concentrations. The plants were tended according to these treatments and after 65 days the average number and weight of the tomatoes per plant were measured for each treatment group. Which of the following is an explanatory variable in this study? Check all that apply. -Fertilizer schedule -Number of days of treatment -Number of plants per planter -Number of tomatoes per plant -Watering schedule
Fertilizer schedule Watering schedule
The weights (in pounds) and cholesterol levels (in mg/dL) of several individuals was observed. The data are shown in the scatterplot below: The outlier on the graph is likely due to an error in recording the data. Which of the following statements is true? -A reasonable value of the correlation coefficient r for these data is 1.2. -If the weight (WT) were measured in kilograms instead of pounds (1 lb = 0.4536 kg) the value of r would change accordingly. -If the outlier were removed, the correlation coefficient (r) would increase. -If the outlier were removed, the correlation coefficient (r) would decrease.
If the outlier were removed, the correlation coefficient (r) would increase.
The boxplots below display annual incomes (in thousands of dollars) for households in two cities. Which city has a greater percentage of households with annual incomes between $50,000 and $80,000? -Statstown -Medianville -Both cities have the same percentage of households with annual incomes between $50,000 and $80,000. -It is impossible to tell from the boxplots.
Medianville
Which of the following is an important advantage of experiments over observational studies? Check all that apply. -Ensuring that each subject in the trial receives the best possible treatment -Isolating the effects of a specific treatment -Guaranteeing that approximately the same number of subjects is assigned to each treatment group -Controlling for lurking variables to have a stronger case for causation
Isolating the effects of a specific treatment Controlling for lurking variables to have a stronger case for causation
The boxplots below show the real estate values of single-family homes in two neighboring cities (in thousands of dollars). Which city has more households? -Statstown -Medianville -Both cities have the same number of households. -It is impossible to tell from the boxplots
It is impossible to tell from the boxplots
The boxplots below show the number of marshmallows in a bag, as estimated by students in two elementary school classes. Which class has more students?? -Ms. Apple's class -Ms. Banana's class -Both classes have the same number of students. -It is impossible to tell from the boxplots.
It is impossible to tell from the boxplots.
A survey was conducted from a random sample of 8225 Americans, and one variable that was recorded for each participant was their answer to the question, "How old are you?" The mean of this data was found to be 42, while the median was 37. What does this tell you about the shape of this distribution? -It is skewed left. -There is not enough information. -It is skewed right. -It is symmetric.
It is skewed right.
In a 2003 study by Bertrand and Mullainathan to measure racial discrimination in the labor market, experimenters sent fictitious resumes to help-wanted ads in Boston and Chicago newspapers. To manipulate perception of race each resume was assigned either a very African American-sounding name or a very White sounding name. They then measured the response to the resumes. Which of the following is a correct statement about this study? -It was not a blind study because the experimenters knew where they were sending the resumes. -It was not a blind study because there was no placebo. -It was a blind study because those who received the resumes did not know the treatment they received. -It was problematic because the subjects didn't even know they were in an experiment.
It was a blind study because those who received the resumes did not know the treatment they received.
In a recent study to establish the effectiveness of a new cancer drug, subjects were randomly divided into three groups. Group A got a known and effective cancer drug, group B got the new experimental compound, and group C got a combination of the two drugs. None of the individuals nor the nurses knew group assignments, and nurses administering the drugs did not know what drug was being administered to their patients. Which of the following is a correct statement about this study? -It was not a blind study because there was no placebo. -It was not a blind study because patients knew they were participating in a study. -It was a double-blind study because neither the subject nor the experimenter knew what the treatment for a patient was. -It was a blind study because subjects did not know the treatment they were receiving.
It was a double-blind study because neither the subject nor the experimenter knew what the treatment for a patient was.
Here are two datasets: Dataset A: 64 65 66 68 70 71 72 Dataset B: 64 65 66 68 70 71 720 For dataset A, the mean and median are 68. Looking at dataset B, notice that all of the observations except the last one are close together. Which measure will be affected by this last observation in dataset B? -Mean -Median
Mean
In order to obtain a sample of undergraduate students in the United States, a simple random sample of 10 states is selected. From each of the selected states, 10 colleges or universities are chosen at random. Finally, from each of these 100 colleges or universities, a simple random sample of 20 undergraduate students is selected. Thus, the final sample consists of 2,000 undergraduates. This is an example of which type of sampling strategy? -Simple random sampling -Multistage sampling -Convenience sampling -Stratified sampling
Multistage sampling
For their 1992 study, "The Effect of Country Music on Suicide" (published in Social Forces, vol. 71, p. 211), researchers Stack and Gundlach investigated various American communities, recording the number of minutes of daily radio airtime devoted to country songs and the suicide rate. They found a moderately strong positive correlation. In their paper, the researchers explain the results by saying that "the themes found in country music foster a suicidal mood" (emphasis added). A news headline (The Independent [London], October 1, 2004, p. 15) about the research echoed these sentiments when it said, "Strange But True: Country Music Saps Will to Live." The research is even cited on various suicide-prevention websites, some with headings such as "Country Music Increases Suicide Risk." Based on this study, can we have confidence in causality between country music and suicide? -No, causality can be demonstrated only by investigating the entire population. -Yes, causality is indicated by the moderately strong correlation. -No, because the lack of assignment of communities to different levels of country music listening means there is a possibility of lurking variables. -Yes, since different communities listened to different levels of country music, meaningful experimental comparisons can be made. -Yes, as long as the communities were sampled randomly, and the number of communities (the sample size) was sufficiently large.
No, because the lack of assignment of communities to different levels of country music listening means there is a possibility of lurking variables.
In a study conducted by Frantzen and colleagues from 2001 through 2004, researchers studied the consumption of ready-to-eat cereal (RTEC) with the body mass index (BMI) of 625 low-income minority fourth- to sixth-grade students living in San Antonio, Texas. (Students were randomly selected.) They measured students' age, ethnicity, height, and weight and students were administered dietary interviews at the beginning of their fourth-grade year and the end of their fifth- and sixth-grade years. They found a "significant inverse relation between the BMI percentile and the frequency of RTEC consumption" and concluded that "children who frequently consumed RTEC had greater intakes of essential nutrients at baseline and significantly lower BMI over a 3-year period." Is it safe for us to conclude that there is a causal relationship between regular consumption of RTEC and the drop in BMI? -No, because while the relationship is interesting, there is a possibility of lurking variables not studied by the authors. -No, because causality can be demonstrated only by investigating the entire population. -Yes, because causality is indicated by the significant inverse relation. -Yes, because the students were randomly selected for the study. -No, because an inverse relation indicates that there is no causality.
No, because while the relationship is interesting, there is a possibility of lurking variables not studied by the authors.
A student survey was conducted at a major university, and data were collected from a random sample of 750 undergraduate students. One variable that was recorded for each student was the student's answer to the question "With whom do you find it easiest to make friends? Opposite sex/same sex/no difference." These data would be best displayed using which of the following? -Pie chart -IQR -Boxplot -Histogram -Stemplot
Pie chart
A local ice cream shop kept track of the number of cans of cold soda it sold each day, and the temperature that day, for 2 months during the summer. The data are displayed in the scatterplot below: Which of the following is the best description of the relationship between X and Y as it appears in the scatterplot? -Positive linear relationship with outlier(s) -Positive linear relationship with no outlier(s) -Positive nonlinear relationship with outlier(s) -Negative linear relationship with no outlier(s) -Negative nonlinear relationship with outlier(s) -Negative nonlinear relationship with no outlier(s)
Positive linear relationship with outlier(s)
The following scatterplot shows the relationship between the amount of money spent (budget) and the amount of money earned (gross) for the 13 Hollywood movies with the highest profit. Which of the following best describes the relationship between X(budget) and Y(gross) as it appears in the scatterplot? -Negative linear relationship -Positive linear relationship -Positive nonlinear relationship -Negative nonlinear relationship
Positive nonlinear relationship
Based on the results of a nationwide study, the number of contacts programmed into cell phones are summarized on the following boxplot: Choose the correct label for the point on the boxplot represented by the question mark: -Minimum -Q1 -Median -Q3 -Maximum
Q3
A study seeks to answer the question, "Does Vitamin C level in the breast milk of new mothers reduce the risk of allergies in their breastfed infants?" The study concluded that high levels of vitamin C (measured in mg) were associated with a 30 percent lower risk of allergies in the infants. In this scenario, "levels of vitamin C (measured in milligrams)" is what type of variable? -Categorical OR Quantitative
Quantitative
The histogram below displays the distribution of 50 ages at death due to trauma (accidents and homicides) that were observed in a certain hospital during a week. Which of the following best describes the shape of the histogram? Symmetric -Left-skewed with no outliers -Right-skewed with no outliers -Left-skewed with a possible outlier -Right-skewed with a possible outlier
Right-skewed with a possible outlier
This histogram shows the times, in minutes, required for 25 rats in an animal behavior experiment to successfully navigate a maze. Which of the following best describes the shape of the histogram? Symmetric -Left-skewed with no outliers -Right-skewed with no outliers -Left-skewed with a possible outlier -Right-skewed with a possible outlier
Right-skewed with a possible outlier
In order to study whether IQ level is related to birth order, data were collected from a sample of 540 students on their birth order (Oldest/In Between/Youngest) and their score on an IQ test. Which of the following would be a meaningful display of the data from this study? -A histogram -A pie chart -Side-by-side boxplots -A scatterplot -A two-way table
Side-by-side boxplots
In order to study whether there is a relationship between gender and age at marriage, 50 couples were randomly selected and the age of the bride and groom were recorded. Which of the following would be a meaningful display of the data from this study? -A histogram -A two-way table -A pie chart -Side-by-side boxplots -A scatterplot
Side-by-side boxplots
The boxplots below display annual incomes (in thousands of dollars) of households in two cities. Which city has greater variability in income? -Statstown -Medianville -Both cities have the same variability in income. -It is impossible to tell from the boxplots.
Statstown
Which of the tables is the appropriate table of conditional percentages to discover if the region where one lives affects whether or not one has health insurance? -Table A -Table B -Table C
Table A
The cost of taking your pet aboard the air flight with you in the continental US varies according to the airlines. The five number summary for prices based on a sample of major U.S. airlines was: Min = 60, Q1 = 100, Median = 110, Q3 = 125, Max = 150 Which of the following is true about this data? -The lowest price is an outlier. -The highest price is an outlier. -The data is skewed left. -The data is skewed right.
The lowest price is an outlier.
The histogram below displays the distribution of 50 ages at death due to trauma (accidents and homicides) that were observed in a certain hospital during a week. Assume that the largest observation in this dataset is 90. If this observation were wrongly recorded as 900, then what would happen to the mean and median? -Neither the mean nor the median would change. -Both the mean and the median would change. -The mean would stay the same, but the median would change. -The mean would decrease, but the median would not change. -The mean would increase, but the median would not change
The mean would increase, but the median would not change
This histogram shows the times, in minutes, required for 25 rats in an animal behavior experiment to successfully navigate a maze. Assume that the largest observation in this dataset is 8.6 minutes. If this observation were wrongly recorded as 86, then what would happen to the mean and median? -Neither the mean nor the median would change. -Both the mean and the median would change. -The mean would stay the same, but the median would change. -The mean would decrease, but the median would not change. -The mean would increase, but the median would not change.
The mean would increase, but the median would not change.
The histogram below displays the distribution of 50 ages at death due to trauma (unnatural accidents and homicides) that were observed in a certain hospital during a week. Which of the following are the appropriate numerical measures to describe the center and spread of the above distribution? -The median and the IQR -The mean and the standard deviation -The mean and the median -The IQR and the standard deviation
The median and the IQR
The histogram below shows the times, in minutes, required for 25 rats in an animal behavior experiment to successfully navigate a maze. Which of the following are the appropriate numerical measures to describe the center and spread of the above distribution? -The median and the IQR -The IQR and the standard deviation -The mean and the median -The mean and the standard deviation
The median and the IQR
The data in the scatterplot below are an individual's age (in years) and the expected life span (in years). The circles correspond to females and the x's to males. Which of the following conclusions is most accurate? -There is a positive correlation between gender and life expectancy. -There is a negative correlation between gender and life expectancy. -There is a positive correlation between age and life expectancy for both males and females. -There is a negative correlation between age and life expectancy for both males and females.
There is a negative correlation between age and life expectancy for both males and females.
The data in the scatterplot below are an individual's weight and the time it takes (in seconds) on a treadmill to raise his or her pulse rate to 140 beats per minute. The o's correspond to females and the +'s to males. Which of the following conclusions is most accurate? -There is a negative correlation between time and weight for males and for females. -There is a positive correlation between time and weight for males and for females. -There is a positive correlation between gender and weight. -There is a negative correlation between gender and weight.
There is a negative correlation between time and weight for males and for females.
Suppose that the correlation r between two quantitative variables was found to be r = 0. Which of the following is the best interpretation of this correlation value? -There is a strong linear relationship between the two variables. -There is no linear relationship between the two variables. -There is a strong relationship between the two variables. -There is no relationship between the two variables.
There is no linear relationship between the two variables.
In the coastal United States, there is an established correlation between ice cream sales and shark attacks. Which of the following might we conclude from this data? -There may be a third variable that creates a link between ice cream sales and shark attacks. -Eating ice cream may increase the likelihood of a shark attack. -Increases in shark attacks may increase ice cream sales. -This is an anomaly and there is no relationship between shark attacks and ice cream sales.
There may be a third variable that creates a link between ice cream sales and shark attacks.
Suppose a study finds a positive correlation between the number of TV sets in the home of high school seniors and their admission rate into college. Which of the following might we conclude from this data? -There may be a third variable that creates a link between the number of TVs in the home and college admission rate. -Better students tend to have a TV set available. -The increase in home TV sets improves the likelihood of college admission. -This is an anomaly and there is no relationship between TVs in the home and college admission rate.
There may be a third variable that creates a link between the number of TVs in the home and college admission rate.
A simple random sample of 1,240 adult Americans is selected, and each person is asked the following question: In light of candidate Jones's alleged criminal activity do you believe he should withdraw from the race? -67% of those surveyed agreed that he should withdraw. Which of the following is an appropriate conclusion about the results? -They probably overstate the percentage of people who favor his withdrawal because of the question's wording. -They are inaccurate because of convenience sampling. -They are reasonably accurate because the study used a large simple random sample. -They are inaccurate because of voluntary response. -They probably understate the percentage of people who favor his withdrawal because of the question's wording.
They probably overstate the percentage of people who favor his withdrawal because of the question's wording.
A simple random sample of 1,110 adult Americans is selected, and each person is asked the following question: In light of the huge national deficit, should the government at this time spend additional money to establish a national system of health insurance? Only 39% of respondents answered yes. Which of the following is an appropriate conclusion about the results of this summary? -They are reasonably accurate because the study used a large simple random sample. -They probably understate the percentage of people who favor a system of national health insurance because of the question's wording. -They are inaccurate because of voluntary response. -They probably overstate the percentage of people who favor a system of national health insurance because of the question's wording. -They are inaccurate because of convenience sampling.
They probably understate the percentage of people who favor a system of national health insurance because of the question's wording.
A study was done on the timeliness of flights categorized as either "on time" or "delayed" of two major airlines: StatsAir and AirMedian. Data were collected over a period of time from five major cities and it was found that StatsAir does better overall (i.e., has a smaller percentage of flights categorized as delayed). However, in each of the five cities separately, AirMedian does better (i.e., has a smaller percentage of flights categorized as delayed in each city). Which of the following is correct? Check all that apply. -This is an example of Simpson's paradox. -"City" is a lurking variable in this example. -This is an example of a negative association between variables.
This is an example of Simpson's paradox. "City" is a lurking variable in this example.
It is known that, in the United States, well-educated people are less likely to smoke. But what about other nations, where there may be different cultures and/or attitudes toward smoking? In a 1998 study of the relationship between education and smoking in France, a random sample of 334 French men was classified according to their education level (elementary, high-school, or university) and their smoking habits (smoker or nonsmoker). Which of the following statements about this study is correct? -This study is an observational study, since researchers did not assign the men to be smokers or non-smokers, or to one of the education levels. -This study is an experiment, since it was based on a random sample. -This study is an experiment, since each subject was classified into one of the six possible combinations of education level and smoking habits. -This study is a combination of both an experiment and an observational study.
This study is an observational study, since researchers did not assign the men to be smokers or non-smokers, or to one of the education levels.
In a study to determine the relationship between self esteem and eating, subjects had been randomly divided into two groups. One group of subjects were individually told something intended to boost their self esteem while in the other group subjects were individually told something intended to lower their self esteem. Each subject was then individually led into a room alone and asked to count the number of chocolate chip cookies in a very large container and told they could eat as many as they liked while conducting their count. Researchers then counted the number of cookies eaten by subjects in each group. Which of the following statements is true regarding this study? Check all that apply. -This study is an observational study. -This study is blind. -This study is an experimental study. -The treatment was the number of cookies eaten.
This study is an observational study. This study is an experimental study.
To test an herbal treatment for depression, 100 volunteers who suffered from mild depression were randomly divided into two groups. Each person was given a month's supply of tea bags. For one group, the tea contained the herb mixed with spice tea, whereas for the other group, the bags contained only the spice tea. Participants were not told which type of tea they had, and were asked to drink one cup of tea per day for a month. At the end of the month, a psychologist evaluated them to determine if their mood had improved. The psychologist did not know which of the subjects had the tea with the herbal ingredient added. Which of the following statements is true regarding this study? Check all that apply. -This study is an observational study. -This study is double-blind. -The "only spice tea" group serves as the control group.
This study is double-blind. The "only spice tea" group serves as the control group.
The boxplots below show the real estate values of single-family homes in two neighboring cities (in thousands of dollars). Which city has a greater percentage of homes with real estate values between $55,000 and $85,000? -Tinytown -BigBurg -Both cities have the same percentage of homes with real estate values between $55,000 and $85,000. -It is impossible to tell from the boxplots.
Tinytown
When conducting a survey, which of the following is the most important reason to use a random sample? -To get a significant result -To ensure truthful answers to the survey's questions -To avoid bias and to get a representative sample -So that we can make causal conclusions
To avoid bias and to get a representative sample
In a study, which of the following is the most important reason to use random allocation of subjects to the different treatments? -To ensure that each subject in the trial receives the best possible treatment -To protect the experimenters from legal action in the event that the experiment goes drastically awry -To guarantee that the results of the experiment can never be duplicated -To guarantee that approximately the same number of subjects is assigned to each treatment group -To ensure that the different treatment groups are as similar as possible in every way except for the treatment received
To ensure that the different treatment groups are as similar as possible in every way except for the treatment received
Which of the following is an extremely important design element to have in an experimental study? Check all that apply. -Treatments that are imposed by the experimenter -A placebo -Groups which are exactly the same size -Randomized selection of participants
Treatments that are imposed by the experimenter Randomized selection of participants
The city council hired three college interns to measure public support for a large parks and recreation initiative in their city. The interns mailed surveys to 500 randomly selected participants in the current public recreation program. They received 150 responses. True or false? Even though the sample is random, it is not representative of the population of interest. -True -False
True
Research Question: What is the combined effect of medication and diet on blood pressure in adult males? A randomized, controlled experiment investigated this question using a random sample of 540 adult males as subjects. At the beginning of the study, researchers measured the blood pressure of all the subjects. Each subject was given a month's supply of either Drug A, Drug B, or a placebo, then was assigned to be on either a low-fat diet or a low-salt diet for that month-long period. At the end of the month, the researchers measured the blood pressure of each subject again, and compared the two blood pressure readings. Which of the following is an explanatory variable in this study? Check all that apply. -Blood pressure before the study -Blood pressure after the study -Difference in the two measurements of blood pressure -Type of drug given -Type of diet
Type of drug given Type of diet
Here are the number of hours that 9 students spend on the computer on a typical day: 1 6 7 6 8 11 6 12 15 The data from the above 9 students form what type of distribution? -Unimodal -Ultimodal -Bimodal
Unimodal
When surveying subjects about sensitive or self-incriminating topics, what technique might be used to help ensure that individuals answer sensitive or self-incriminating questions honestly? -Using randomized response -Using simple, direct questions -Asking technically complex questions -Asking questions in random order
Using randomized response
The cost of taking your pet aboard the air flight with you in the continental US varies according to the airlines. The five number summary for prices based on a sample of major US airlines was: Min = 60, Q1 = 100, Median = 110, Q3 = 125, Max = 150 If we were to build the box plot for this data, the box would stretch between which two values? What would be the lowest value and highest value?
What would be the lowest value: 100 highest value:125
A researcher wants to determine if preschool attendance is associated with high school graduation for low-income students. She randomly assigns low-income children to two groups; one group will attend preschool program, the second group will not attend preschool. The researcher plans to follow the children in the study for 20 years and observe whether or not they graduate from high school. Which of the following is the explanatory variable in this study? -Whether or not a subject graduates high school -Whether or not a subject attends preschool -The income status of the children -The length of time it takes a subject to graduate high school
Whether or not a subject attends preschool
A researcher wants to determine if preschool attendance is associated with high school graduation for low-income students. She randomly assigns low-income children to two groups; one group will attend preschool program, the second group will not attend preschool. The researcher plans to follow the children in the study for 20 years and observe whether or not they graduate from high school. Which of the following is the response variable in this study? -The income status of the children -The length of time it takes a subject to graduate high school -Whether or not a subject attends preschool -Whether or not a subject graduates high school
Whether or not a subject graduates high school
When conducting a survey, which of the following is the most important reason to avoid using a volunteer sample? -In order to get stronger opinions expressed. -To ensure truthful answers to the survey's questions. -You might not get a significant result. -Your conclusions could not be reliably generalized to a larger population.
Your conclusions could not be reliably generalized to a larger population.
