Statistics Inferring and Sampling

If you survey every third house on a street, what type of sampling technique are you using?

A teacher puts all her students' names in hat, then selects 3 names from the hat. These students will take a standardized test.

• Convenience

• Systematic

• Stratified

• Simple Random

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

• Convenience

• Systematic

• Stratified

• Simple 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

True or False: all samples lead to a good prediction about an entire population.

• True

• False

Sampling can be used to make an inference (or educated guess) about a population.

• True

• False

A researcher asked five of his doctor friends if they thought the new Brand X medicine that he developed was effective. Four responded "yes." The researcher used the results to write a TV advertisement claiming that "4 out of 5 doctors prefer Brand X medicine." Is this a valid inference? Explain.

• No, because the doctors asked are not a representative sample of the population of doctors.

• No, because 4 doctors said yes out of 9 who were asked.

• Yes, because the doctors asked are a representative sample of the population of doctors.

• Yes, because 4 doctors said yes out of the 5 who were asked.

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 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