Exam 7: Data for Decisions

Which of the following sampling method is unbiased?

To determine the proportion of students at a university who favors the construction of a parking garage, a sample of people driving through the student center parking lot is surveyed and it is found that 45% favor the garage. The actual proportion of the student body who favors the garage is 40%. This difference is most likely an example of sampling:

Which of the following sampling techniques is most likely to produce biased results?

If the confidence interval is determined to be from 56% to 62%, then the margin of error is:

Use the random digits table above, starting at line 104, to choose four people from a list numbered 001 to 500 to call for a poll.

A poll of 80 students selected at random at Midtown University found that 20 were in favor of a fee increase to support extra maintenance of gardens on campus. In the example, the sample proportion is:

A dummy medication (such as a salt tablet) will often help a patient who trusts the doctor who administers the medicine. This is called:

A polling company working for a candidate for governor surveys a sample of 2500 registered voters in the state to determine if they are in agreement with the candidate's stand on gun control. Describe the population for this study.

A school superintendent believes a new approach to teaching children to read will produce better standardized test scores in the district. Describe how the superintendent may design a randomized comparative experiment to test this theory.

Consider the following situation: Doctors identify 500 women, half of whom had mothers with breast cancer and half of whom did not. The medical records of the women are followed up for 20 years to determine if heredity plays a role in breast cancer. This describes a prospective study.

Use the random digits table above, starting at line 105, to select four people from a list numbered 00 to 99.

Consider the following situation: A group of 300 students is randomly selected at a local high school and required to fill out yearly questionnaires on family income. Students' performances on standardized tests are then followed throughout their high school years to determine if socioeconomic status affects SAT scores. This describes an experiment.

You wish to survey the students at your college to determine their feelings about the quality of services in the student center. Which of the following sampling designs is best for avoiding bias?

A polling company conducted a survey of voters to obtain data for a political campaign. They selected 3500 voters randomly from the 16,800 names on the voter registration lists of the county and found that 1365 intended to vote for candidate Doe. The sample proportion is:

To estimate the proportion of voters in a town likely to favor a tax increase for road repair, a random sample of people chosen from the voter registration list is surveyed and the proportion who favors the increase is found to be 43%. The actual proportion in the town is 40%. This difference is most likely an example of sampling:

Explain the difference between bias and variability in sampling results.

A marketing company conducts a survey of college students to obtain data for a marketing campaign. They randomly select five in-state colleges and then randomly choose 100 students from the registration lists of these colleges. This type of sample is a:

When an accurate and complete list of the population is not available, a sampling will suffer from:

A marketing company conducted a survey of college students to obtain data for an advertising campaign. They selected 1421 students randomly from campus directories of 132 colleges and universities. The students in the directories at the 132 colleges and universities represent:

You take a simple random sample of 500 from a large population. If the population proportion is p = 0.2, describe the sampling distribution in terms of shape, center and variability.