TEST BANK OF ELEMENTARY STATISTICS LATEST UPDATE

TEST BANK OF ELEMENTARY STATISTICS LATEST UPDATE What is an observational study? A. An observational study is a list of all individuals in a population along with certain characteristics of each individual. B. An observational study is when a researcher assigns individuals to a certain group, intentionally changing the value of an explanatory variable, and then recording the value of the response variable for each group. C. An observational study measures the value of the response variable without attempting to influence the value of either the response or explanatory variables. - CORRECT ANSWER-C What is a designed experiment? A. A designed experiment measures the value of the response variable without attempting to influence the value of either the response or explanatory variables. B. A designed experiment is when a researcher assigns individuals to a certain group, intentionally changing the value of an explanatory variable, and then recording the value of the response variable for each group. C. A designed experiment is a list of all individuals in a population along with certain characteristics of each individual. - CORRECT ANSWER-B What allows the researcher to claim causation between an explanatory variable and a response variable? - CORRECT ANSWER-A designed experiment What is meant by confounding? - CORRECT ANSWER-It exists in a study when the effects of two or more explanatory variables are not separated. So any relation that appears to exist between a certain explanatory variable and the response variable may be due to some other variable not accounted for in the study What is a lurking variable? - CORRECT ANSWER-Not accounted for in the study but affects the value of the response variable What is a confounding variable? - CORRECT ANSWER-A confounding variable is an explanatory variable that was considered in a study whose effect cannot be distinguished from a second explanatory variable in the study. Determine whether the study depicts an observational study or an experiment. A study is conducted to determine if there is a relationship between lung capacity and proximity to coal mines. A sample of 100 people living within 1 mile of a coal mine is collected and their lung capacity measured. Does the description correspond to an observational study or an experiment? - CORRECT ANSWER-The study is an observational study because the study examines individuals in a sample, but does not try to influence the response variable. Determine whether the study depicts an observational study or an experiment. Seventh-grade students are randomly divided into two groups. One group is taught math using traditional techniques. The other is taught math using a reform method. After 1 year, each group is given an achievement test to compare its proficiency with that of the other group. - CORRECT ANSWER-The study is an experiment because the researchers control one variable to determine the effect on the response variable. What is a frame? - CORRECT ANSWER-A list of the individuals in the population we are studying What does it mean when sampling is done without replacement? - CORRECT ANSWER-Once an individual is selected, the individual cannot be selected again. What sampling method does not require a frame? - CORRECT ANSWER-systematic obtained by dividing the population into groups and selecting all individuals from within a random sample of the groups. - CORRECT ANSWER-cluster sample obtained by dividing the population into homogeneous groups and randomly selecting individuals from each group. - CORRECT ANSWER-stratified sample To estimate the percentage of defects in a recent manufacturing batch, a quality control manager at Daimler-Chrysler selects every 19th van that comes off the assembly line starting with the second until she obtains a sample of 110 vans. What type of sampling is used? - CORRECT ANSWER-Systematic To determine customer opinion of their safety features, Daimler-Chrysler randomly selects 80 service centers during a certain week and surveys all customers visiting the service centers. What type of sampling is used? - CORRECT ANSWER-Cluster Apple wants to administer a satisfaction survey to its current customers. Using their customer database, the company randomly selects 80 customers and asks them about their level of satisfaction with the company. What type of sampling is used? - CORRECT ANSWER-Simple random A television station asks its viewers to call in their opinion regarding the desirability of programs in high definition TV. What type of sampling is used? - CORRECT ANSWER-Convenience To determine her blood sugar level, Charlotte divides up her day into three parts: morning, afternoon, and evening. She then measures her blood sugar level at 2 randomly selected times during each part of the day. What type of sampling is used? - CORRECT ANSWER-Stratified What is a closed question? What is an open question? - CORRECT ANSWER-A closed question has fixed choices for answers, whereas an open question is a free-response question. Discuss the advantages and disadvantages of each type of question (closed/open). - CORRECT ANSWER-Since closed questions limit the possible responses, they are easier to analyze. Open questions are harder to analyze due to the variety of answers and the chance of misinterpreting an answer. What does it mean when a part of the population is under-represented? - CORRECT ANSWER-When a part of the population is proportionally smaller in a sample than in its population, this part of the population has been under-represented. This could be caused by many different types of bias, or even by random chance. Distinguish between nonsampling error and sampling error. - CORRECT ANSWER-Nonsampling error is the error that results from the process of obtaining the data. Undercoverage, nonresponse bias, response bias, or data-entry errors are all types of nonsampling errors. Sampling error is the error that results because a sample is being used to estimate information about a population. This type of error occurs because a sample gives incomplete information about a population. The manager of a shopping mall wishes to expand the number of shops available in the food court. She has a market researcher survey the first 100 customers who come into the food court during weekend mornings to determine what types of food the shoppers would like to see added to the food court. The survey has bias. Determine whether the flaw is due to the sampling method or the survey itself. For biased surveys, identify the cause of the error. What is the cause of the bias? What is the best way to remedy this problem? - CORRECT ANSWER-Sampling Bias; Ask customers throughout the day on both weekdays and weekends. The survey has a bias. An abortion rights advocate wants to estimate the percentage of people who favor opening abortion clinics. She conducts a nationwide survey of 1950 randomly selected adults 18 years and older. The interviewer asks the respondents, "Do you favor supporting women's rights by keeping abortion clinics open question mark " What best describes the bias in the survey? How can the bias be remedied? - CORRECT ANSWER-Response bias; The interviewer should reword the question. The