Sampling Methods and Sampling Bias

The president of a college randomly selects 2 students from each department to serve on a student advisory board.

• Convenience

• Systematic

• Stratified

• Simple Random

State the type of sample.

In order to determine the average IQ of ninth-grade students, a school psychologist obtains a list of all schools in the local public school system. She randomly selects five of these schools and administers an IQ test to all ninth-grade students at the selected schools.

• Stratified Random Sample

• Cluster Sample

• SRS

• Random Sample

Which of the following doesn’t result in some form of bias?

• Choosing AP students to survey regarding their GPA in order to estimate the average GPA in a school.

• Polling a group of potential voters outside a Republican campaign office in order to estimate the proportion of city residents who favor a particular candidate.

• Surveying people who work in the marketing department of a large corporation in order to assess employee satisfaction with management policies.

• Choosing a stratified random sample of juniors and seniors at a high school in order to estimate the proportion of juniors and seniors who plan to go on to college.

• Asking shoppers leaving a grocery store if they think groceries should cost less in order to estimate the proportion of city residents who think groceries cost too much.

A teacher wants to know the average time spent doing homework by the students in her class of 20 girls and 5 boys.

She selects the five closest to her desk.

• simple random

• Self Selected.

• Convenience

• Systematic Random

A teacher wants to know the average time spent doing homework by the students in her class of 20 girls and 5 boys.

She picks the student in every 5th seat.

• Simple Random

• Systematic

• voluntary response

• convenience

A political polling group is interested in learning about the proportion of registered voters who favor a particular candidate for mayor. Which of the following sampling plans may have introduced bias?

• Individuals were selected randomly to participate from a list of registered voters.

• Every 50^th person on a list of registered voters was contacted and asked to identify who they would vote for in the upcoming election.

• A list of registered voters was first separated into two lists—one of males and one of females. Then individuals were selected at random from each of the two lists.

• A survey was mailed to all registered voters and those who returned the survey make up the sample

• None of the above sampling plans creates the potential for bias.

A department store mails a customer satisfaction survey to people who make credit card purchases at the store. This month, 45,000 people made credit card purchases. Surveys are mailed to 1000 of these people, chosen at random, and 137 people return the survey form. Identify the population and the sample.

• P: 45,000 people who made credit card purchases.

  S: 137 returned surveys.

• P: 1,000 people that made credit card purchases who received a survey

  S: 137 returned surveys.

• P: 45,000 people who made credit card purchases.

  S: 1,000 people that made credit card purchases who received a survey

• P: All people who that have made credit card purchases.

  S: 1,000 people that made credit card purchases who received a survey

Assign each car in a dealership a number and then use a random-number table to select the cars to be inspected.

• systematic

• simple random sample

• convenience

• Self - selected (volunteer)

Interview every 10th student who enters the school in the morning.

• simple random

• voluntary response

• systematic

• convenience

Identify the sampling design: Mr. Rhoades puts all of his students' names in a hat and randomly selects one without looking.

• cluster

• volunteer

• systematic

• simple random