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In Exercises 17 ? to 23 ?, for the reports about statistical studies, identify the following items (if possible). If you can't tell, then say so - this often happens when we read about a survey. a. The population b. The population parameter of interest c. The sampling frame d. The sample e. The sampling method, including whether or not randomization was employed f. Who (if anyone) was left out of the study g. Any potential sources of bias you can detect and any problems you see in generalizing to the population of interest Soil samples The Environmental Protection Agency took soil samples at 16 locations near a former industrial waste dump and checked each for evidence of toxic chemicals. They found no elevated levels of any harmful substances.

In Exercises 17 ? to 23 ?, for the reports about statistical studies, identify the following items (if possible). If you can't tell, then say so - this often happens when we read about a survey. a. The population b. The population parameter of interest c. The sampling frame d. The sample e. The sampling method, including whether or not randomization was employed f. Who (if anyone) was left out of the study g. Any potential sources of bias you can detect and any problems you see in generalizing to the population of interest Roadblock State police set up a roadblock to estimate the percentage of cars with up-to-date registration, insurance,and safety inspection stickers. They usually find problems with about \(10 \%\) of the cars they stop.

In Exercises 17 ? to 23 ?, for the reports about statistical studies, identify the following items (if possible). If you can't tell, then say so - this often happens when we read about a survey. a. The population b. The population parameter of interest c. The sampling frame d. The sample e. The sampling method, including whether or not randomization was employed f. Who (if anyone) was left out of the study g. Any potential sources of bias you can detect and any problems you see in generalizing to the population of interest Snack foods A company packaging snack foods maintains quality control by randomly selecting 10 cases from each day's production and weighing the bags. Then they open one bag from each case and inspect the contents.

In Exercises 17 ? to 23 ?, for the reports about statistical studies, identify the following items (if possible). If you can't tell, then say so - this often happens when we read about a survey. a. The population b. The population parameter of interest c. The sampling frame d. The sample e. The sampling method, including whether or not randomization was employed f. Who (if anyone) was left out of the study g. Any potential sources of bias you can detect and any problems you see in generalizing to the population of interest Milk samples Dairy inspectors visit farms unannounced and take samples of the milk to test for contamination. If the milk is found to contain dirt, antibiotics, or other foreign matter, the milk will be destroyed and the farm reinspected until purity is restored.

Mistaken poll A local TV station conducted a "PulsePoll" about the upcoming mayoral election. Evening news viewers were invited to text in their votes, with the results to be announced on the late-night news. Based on the texts, the station predicted that Amabo would win the election with \(52 \%\) of the vote. They were wrong: Amabo lost, getting only \(46 \%\) of the vote. Do you think the station's faulty prediction is more likely to be a result of bias or sampling error? Explain.

Parent opinion, part 1 In a large city school system with 20 elementary schools, the school board is considering the adoption of a new policy that would require elementary students to pass a test in order to be promoted to the next grade. The PTA wants to find out whether parents agree with this plan. Listed below are some of the ideas proposed for gathering data. For each, indicate what kind of sampling strategy is involved and what (if any) biases might result. a. Put a big ad in the newspaper asking people to log their opinions on the PTA website. b. Randomly select one of the elementary schools and contact every parent by phone. c. Send a survey home with every student, and ask parents to fill it out and return it the next day. d. Randomly select 20 parents from each elementary school. Send them a survey, and follow up with a phone call if they do not return the survey within a week.

Churches For your political science class, you'd like to take a survey from a sample of all the Catholic church members in your city. A list of churches shows 17 Catholic churches within the city limits. Rather than try to obtain a list of all members of all these churches, you decide to pick 3 churches at random. For those churches, you'll ask to get a list of all current members and contact 100 members at random. a. What kind of design have you used? b. What could go wrong with your design?

Playground Some people have been complaining that the children's playground at a municipal park is too small and is in need of repair. Managers of the park decide to survey city residents to see if they believe the playground should be rebuilt. They hand out questionnaires to parents who bring children to the park. Describe possible biases in this sample.

Roller coasters An amusement park has opened a new roller coaster. It is so popular that people are waiting for up to 3 hours for a 2-minute ride. Concerned about how patrons (who paid a large amount to enter the park and ride on the rides) feel about this, they survey every 10 th person on the line for the roller coaster, starting from a randomly selected individual. a. What kind of sample is this? b. What is the sampling frame? c. Is it likely to be representative? d. What members of the population of interest are omitted?

Playground, act two The survey described in Exercise 29 ? asked: Many people believe this playground is too small and in need of repair. Do you think the playground should be repaired and expanded even if that means raising the entrance fee to the park? Describe two ways this question may lead to response bias.