Stat Exam 1
A five-number summary for a data set is 35, 50, 60, 70, 90. About what percent of the observations are between 35 and 90? -25% -100% -75% -50%
100%
A five-number summary given in Case Study 1.1 for the fastest ever driving speeds reported by 102 women was: 30, 80, 89, 95, 130. What is the interquartile range (IQR) of these data? -9 -6 -15 -100
15
If an exam was worth 100 points, and your score was at the 80th percentile, then: -80% of the class had scores at or above your score. -20% of the class had scores at or above your score. -your score was 80 out of 100. -20% of the class had scores at or below your score.
20% of the class had scores at or above your score.
What is the effect of an outlier on the value of a correlation coefficient? -An outlier will have no effect on a correlation coefficient. -An outlier will always decrease a correlation coefficient. -An outlier might either decrease or increase a correlation coefficient, depending on where it is in relation to the other points. -An outlier will always increase a correlation coefficient.
An outlier might either decrease or increase a correlation coefficient, depending on where it is in relation to the other points.
A counselor at a weight-loss clinic believes that depression has an effect on body mass index (BMI). He gathers data from 45 subjects and finds the coefficient of determination (r^2) between these two variables to be .453. What does this mean? -Depression explains 45.3% of the variation in BMI. -BMI explains 45.3% of the variation in depression. -Depression explains 54.7% of the variation in BMI. -BMI explains 54.7% of the variation in depression.
Depression explains 45.3% of the variation in BMI.
What type of study is this? A sample survey of 100 voters was used to compare the proportion of women in the Democratic and Republican parties. -Single-blind study -Observational study -Double-blind study -Experimental study
Observational study
Which one of the following statements involving correlation is possible and reasonable? -The correlation between the height of a father and the height of his first son is 0.6 -The correlation between left foot length and right foot length is 2.35. -The correlation between hair color and eye color is 0.80. -The correlation between hair color and age is positive.
The correlation between the height of a father and the height of his first son is 0.6
You wish to describe the relationship between exam grades and the amount of time students watch the Discovery Channel. The correlation turns out to be r = +0.30. What does this mean? -The more a student watches the Discovery Channel, the higher his or her exam grades tend to be. -In order to increase your exam grades, it is recommended that you spend more time watching the Discovery Channel. -The more a student watches the Discovery Channel, the lower his or her exam grades tend to be. -30% of the variation in exam grades is explained by the linear relationship with time spent watching the Discovery Channel.
The more a student watches the Discovery Channel, the higher his or her exam grades tend to be.
Which of the following would be most likely to produce selection bias in a survey? -Using a random sample of students at a university to estimate the proportion of people who think the legal drinking age should be lowered. -Only receiving responses from half of the people in the sample. -Using questions with biased wording. -Conducting interviews by telephone instead of in person.
Using a random sample of students at a university to estimate the proportion of people who think the legal drinking age should be lowered.
A regression between foot length (response variable in cm) and height (explanatory variable in inches) for 33 students resulted in the following regression equation: y ^ = 10.9 + 0.23 x What is the predicted foot length for a student who is 73 inches tall? -27.69 cm -33 cm -17.57 cm -29 cm
27.69 cm
A list of 5 pulse rates is: 70, 64, 80, 74, 92. What is the median for this list? -77 -76 -74 -80
74
In a survey, students are asked how many hours they study in a typical week. A five-number summary of the responses is: 2, 9, 14, 20, 60. Which interval describes the number of hours spent studying in a typical week for about 50% of the students sampled? -9 to 4 -9 to 20 -2 to 9 -14 to 20
9 to 20
Very young children who live in homes where the television is on most of the time may have more trouble learning how to read than other kids their age, according to a study of media habits of children up to 6 years old. The report, based on a survey of parents, also found that kids in the 6 months to 6-year-old age group spend about two hours a day watching television, playing a video game or using a computer. That's roughly the same amount of time they spend playing outdoors and three times as long as they spend reading or being read to. What is the response variable in this study? -Television habits in the home -Ability to learn how to read -Time spent playing outside -Age of the child
Ability to learn how to read
Research is done to see whether taking oral contraceptives increases women's blood pressures. The blood pressures of women who take oral contraceptives are compared to the blood pressures of women who do not take oral contraceptive. A complicating factor is that the women who take oral contraceptives tend to be younger than the others. This must be taken into account because blood pressure increases with age. Which variable is a confounding variable in this study? -Blood pressure -Oral contraceptive use -Age -There are no confounding variables in this study
Age
A national polling organization wishes to estimate the percentage of all teenagers who believe social security will 'be there' for them. The organization surveys a random sample of 1500 teenagers and 37% of this sample says that they believe social security will 'be there' for them. In this survey, what is the population of interest? -Teenagers who believe social security will 'be there' for them. -The 1500 teenagers who were surveyed -All teenagers. -The people in the sample who believe social security will 'be there' for them.
All teenagers.
Which one of the following statements is true about sample size and margin of error? -Increasing the sample size of a survey decreases the margin of error. -Increasing the sample size of a survey increases the margin of error. -Increasing the sample size of a survey only changes the margin of error if there is an error (a mistake) in the way the survey is conducted -Increasing the sample size of a survey does not change the margin of error.
Increasing the sample size of a survey decreases the margin of error.
Which of the following is NOT true about drawing a simple random sample from a population? -It requires that the population be represented by a list. -It protects against hidden or unknown biases. -It requires that the size of the sample be no more than 5% of the size of the population. -It gives each member of the population an equal chance of being selected.
It requires that the size of the sample be no more than 5% of the size of the population.
What type of study is this? A tea manufacturer is trying to decide whether to add peach flavoring or mango flavoring to green tea for a new product. A study is done by stopping customers at a grocery store and asking them to drink a small cup of tea with each flavoring, then to rate each of the two flavors on a scale from 1 to 10. The order in which the teas are presented is randomly assigned for each person. -Case-control study -Matched-pairs design study -Sample survey study -Observational study
Matched-pairs design study
What type of study is this? Thirty-six students were randomly assigned to listen to Mozart (18 students) or a relaxation tape (18 students). The IQ of the students were measured afterwards. -Single-blind study -Observational study -Double-blind study -Randomized experimental study
Randomized experimental study
Researchers would like to compare meditation and exercise to see which is more effective for reducing stress. One hundred people who suffer from high stress volunteer to participate in a study for 10 weeks. Participants will either be given a 10-week course in meditation or will participate in a 10-week exercise program. Participants are randomly assigned to one of the two programs and a psychologist measures their stress levels before and after the 10-week program, without being told who is in which program. This experiment would be: -Single-blind because the psychologist doesn't know who is in which program, but the participants do know. -Single-blind as long as the participants are not told the results of the stress level measurements. -Neither single nor double-blind. -Double-blind as long as the participants are not told the results of the stress level measurements.
Single-blind because the psychologist doesn't know who is in which program, but the participants do know.
There are five cities in a politician's district but redistricting has been proposed for the state. The politician would like to know which city he should try to remove from his district. He plans to conduct a survey to find out his approval rating. Which one of the following sampling plans would be most useful for his purposes? -Take a simple random sample across his district. -Take a cluster sample with two of the five cities as clusters. -Take a stratified sample with political parties as the strata. -Take a stratified sample with the five cities as the strata.
Take a stratified sample with the five cities as the strata.
Which one of the following statements is most correct about a skewed dataset? -The mean and median will usually be different. -The mean will always be lower than the median. -The mean and median will usually be the same. -The mean will always be higher than the median.
The mean and median will usually be different.
A researcher conducts a study to determine whether or not taking Vitamin C prevents colds. What is the explanatory variable in this study? -Whether or not one is a participant in the study -Whether or not one gets colds -Whether or not one takes Vitamin C -Whether or not one knows which treatment one is taking
Whether or not one takes Vitamin C
The greater the hours of television watched, the lower the GPA (grade point average). The number of units (credit hours) taken is: -an interacting variable -a response variable -a potential confounding variable
a potential confounding variable
Which one of the following variables is a quantitative variable? -hair color -marital status -gender -age
age
A survey of 1,204 black respondents found that 31% agreed with the statement "American society is fair to everyone" when the race of the interviewer was white, but only 14% agreed when the race of the interviewer was black. The difference between these responses is an example of: -a Hawthorne Effect -extending results inappropriately -an Experimenter Effect -relying on memory or second hand sources
an Experimenter Effect
Which one of these variables is a categorical variable? -weight -number of ear piercings -height -brand of car
brand of car
Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia randomly selects one class among all the foreign language classes taught that year, and then interviews all students in that class, the sampling method is a: -stratified random sample. -systematic sample. -simple random sample. -cluster sample.
cluster sample.
Which one of the following is a variable that we usually put on the horizontal axis of a scatterplot? -explanatory variable -response variable -y variable -dependent variable
explanatory variable
When the results of a study on adults is applied to children, the effect is called: -a cause and effect relationship -a Hawthorne Effect -relying on memory or second hand sources -extending results inappropriately
extending results inappropriately
Consider the following survey question: "Do you agree that the alcohol industry should be banned from targeting teenage girls in their advertising?" Which of the following types of bias is this question an example of? -selection bias -unintentional bias -intentional bias -nonresponse bias
intentional bias
For a survey of American diets a random sample of 1000 people were contacted. Of the 1000 people, 340 people completed the questionnaire. The results of this study, if applied to all Americans, are questionable because of: -selection bias -response bias -nonresponse bias -a large margin of error
nonresponse bias
The simple linear regression equation can be written as y ^ = b 0 + b 1 x. In the simple linear regression equation, the symbol y ^ represents the: -predicted response -explanatory variable -estimated slope -estimated intercept
predicted response
Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia randomly selects 20 students among all students taking a foreign language class that year, the sampling method is a: -cluster sample. -systematic sample. -stratified random sample. -simple random sample.
simple random sample.
Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia randomly selects 5 students from French, 5 from German, 5 from Spanish, and 5 from Chinese, the sampling method is a: -stratified random sample. -systematic sample. -simple random sample. -cluster sample.
stratified random sample.
Two variables have a positive association or relationship when: -the values of one variable tend to decrease as the values of the other variable increase. -the values of one variable tend to increase regardless of how the values of the other variable change -the values of both variables are always positive. -the values of one variable tend to increase as the values of the other variable increase.
the values of one variable tend to increase as the values of the other variable increase.