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Determine whether the study depicts an observational study or an experiment. Conservation agents netted 250 large-mouth bass in a lake and determined how many were carrying parasites.

The survey has bias. (a) Determine the type of bias. (b) Suggest a remedy. To determine the public's opinion of the police department, the police chief obtains a cluster sample of 15 census tracts within his jurisdiction and samples all households in the randomly selected tracts. Uniformed police officers go door to door to conduct the survey.

Professor Andy Neill wanted to determine if the reaction time of people differs in their dominant hand versus their nondominant hand. To do this, he recruited 15 students. Each student was asked to hold a yardstick between the index finger and thumb. The student was asked to open the hand, release the yardstick, and then catch the yardstick between the index finger and thumb. The distance that the yardstick fell served as a measure of reaction time. A coin flip was used to determine whether the student would use their dominant hand first or the nondominant hand. Results indicated that the reaction time in the dominant hand exceeded that of the nondominant hand. (a) What type of experimental design is this? (b) What is the response variable in this study? (c) What is the treatment? (d) Identify the experimental units. (e) Why did Professor Neill use a coin flip to determine whether the student should begin with the dominant hand or the nondominant hand? (f) Draw a diagram similar to Figure \(7,8,\) or 10 to illustrate the design.

Classify the variable as qualitative or quantitative. Grams of carbohydrates in a doughnut

Is there an association between level of happiness and the risk of heart disease? Researchers studied 1739 people over a 10 year period and asked questions about their daily lives and the hassles they face. The researchers also determined which individuals in the study experienced any type of heart disease. After their analysis, they concluded that happy individuals are less likely to experience heart disease. Source: European Heart Journal \(31(9): 1065-1070,\) February \(2010 .\) (a) What type of observational study is this? Explain. (b) What is the response variable? What is the explanatory variable? (c) In the report, the researchers stated that "the research team also hasn't ruled out that a common factor like genetics could be causing both the emotions and the heart disease." Use the language introduced in this section to explain what this sentence means.

Classify the variable as qualitative or quantitative. Number of unpopped kernels in a bag of microwave popcorn

In Problems 11-22, identify the type of sampling used. A survey regarding download time on a certain website is administered on the Internet by a market research firm to anyone who would like to take it.

Is a television (TV) in the bedroom associated with obesity? Researchers questioned 379 twelve-year old adolescents and concluded that the body mass index (BMI) of the adolescents who had a TV in their bedroom was significantly higher than the BMI of those who did not have a TV in their bedroom. Source: Christelle Delmas, Carine Platat, Brigette Schweitzer, Aline Wagner, Mohamed Oujaa, and Chantal Simon. "Association Between Television in Bedroom and Adiposity Throughout Adolescence," Obesity, \(15: 2495-2503,2007\) (a) Why is this an observational study? What type of observational study is this? (b) What is the response variable in the study? What is the explanatory variable? (c) Can you think of any lurking variables that may affect the results of the study? (d) In the report, the researchers stated, "These results remain significant after adjustment for socioeconomic status." What does this mean? (e) Can we conclude that a television in the bedroom causes a higher body mass index? Explain.

Are young couples who marry or cohabitate more likely to gain weight than those who stay single? Researchers followed 8000 men and women for 7 years. At the start of the study, none of the participants were married or living with a romantic partner. The researchers found that women who married or cohabitated during the study gained 9 pounds more than single women, and married or cohabitating men gained, on average, 6 pounds more than single men. (a) Why is this an observational study? What type of observational study is this? (b) What is the response variable in the study? What is the explanatory variable? (c) Identify some potential lurking variables in this study. (d) Can we conclude that getting married or cohabiting causes one to gain weight? Explain.

In Problems 11-22, identify the type of sampling used. The presider of a guest-lecture series at a university stands outside the auditorium before a lecture begins and hands every fifth person who arrives, beginning with the third, a speaker evaluation survey to be completed and returned at the end of the program.