Samples

Define simple random sampling

A sample of size n from a population of size N is obtained through simple random sampling if every possible sample of size n has an equally likely chance of occurring.

A polling organization conducts a study to estimate the percentage of households that places an emphasis on physical activity. It mails a questionnaire to 1413 randomly selected households across the United States and asks the head of each household if he or she places an emphasis on physical activity. Of the 1413 households selected, 40 responded. The survey design is flawed. Which of the following best describes the problem? A. Nonresponse B. Sampling bias C. Response bias

A. Non-response

An anti-drunk driving advocate wants to estimate the percentage of people who favor increasing the penalty for drunk driving. She conducts a nationwide survey of 1570 randomly selected adults 18 years and older. The interviewer asks the respondents, "Do you favor harsher penalties for those convicted for drunk driving? Which type of bias best describes the problem? A. Response bias B. Non-response bias C. Sampling bias

A. Response bias

Suppose you are conducting a survey regarding illicit drug use among teenagers in some school district. You obtain a cluster sample of 12 schools within the district and sample all sophomore students in the randomly selected schools. The survey is administered by the teachers. This survey has bias. What is the type of bias? A. Response bias B. Sampling bias C. Nonresponse bias What is a possible remedy? A. Maybe perform the polling by professional social workers. B. Conduct face-to-face or telephone interview. C. Use systematic random sampling.

A. Response bias A. Maybe perform the polling by professional social workers.

The owner of a shopping mall wishes to expand the number of shops available in the food court. He has a market researcher survey the first 80 customers who come into the food court during the weekend morning to determine what types of food the shoppers would like to see added to the food court. This survey has bias. What is the cause of the bias? A. Sampling bias B. Response bias C. Non-response Which of the following is the best way to remedy this problem? A. Ask customers throughout the day on both weekdays and weekends. B. Reword the question so that is balanced. C. Increase the sample size so that more people respond to the question.

A. Sampling bias A. Ask customers throughout the day on both weekdays and weekends.

A polling organization conducts a study to estimate the percentage of households that speak a foreign language as the primary language. They mail a questionnaire to 1,023 randomly selected households and asks the head of household if a foreign language is the primary language spoken in the home. Of the 1,023 households selected, 12 responded. This survey has bias. What is the type of bias? A. Response bias B. Non-response bias C. Sampling bias What is a possible remedy? A. Conduct face-to-face or telephone interviews. B. Use systematic random sampling. C. Reword the question.

B. Non-response bias A. Conduct face-to-face or telephone interviews.

A creamery is considering opening a new store in another town. Before opening the store, the company would like to know the percentage of households in this town that regularly visit an ice cream shop. The market researcher obtains a list of households and randomly selects 150 of them. He mails a questionnaire to the 150 households that asks about ice cream eating habits. Of the 150 questionnaires mailed, 4 are returned. This survey has a bias. What type of bias? A. Response bias B. Non-response bias C. Sampling bias What is a possible remedy? A. Use systematic random sampling. B. Conduct face-to-face or telephone interviews. C. Reword the question.

B. Non-response bias B. Conduct face-to-face or telephone interviews.

Suppose a random phone survey is being conducted to find the population's feelings on a new stamp design. If the randomly selected person is not home, they are called again later in the day. What tactic is being used to increase the response rate for this survey? A. The company is selecting people randomly. B. The company is using callbacks. C. The company is using a phone survey. D. The company is using an incentive.

B. The company is using callbacks.

A newspaper article reported, "The famous magazine survey of more than 5,000 women aged 18-34 found about 42 percent considered themselves overweight or obese." This survey has bias. What is the type of bias? A. Nonresponse bias B. Sampling bias C. Response bias What is a possible remedy? A. Reword the question. B. Conduct face-to-face or telephone interviews. C. Use systematic random sampling.

B.Sampling bias C. Use systematic random sampling.

A magazine is conducting a study on the effects of infidelity in a marriage. The editors randomly select 400 women whose husbands were unfaithful and ask, "Do you believe a marriage can survive when the husband destroys the trust that must exist between husband and wife?" This survey has bias. What is the type of bias? A. Nonresponse bias B. Sampling bias C. Response bias What is a possible remedy? A. Reword the question. B. Conduct face-to-face or telephone interviews. C. Use systematic random sampling.

C. Response bias A. Reword the question.

To determine customer opinion of their inflight service, Continental Airlines randomly selects 150 flights during a certain week and surveys all passengers on the flights. What type of sampling is used?

Cluster

A newspaper asks its readers to call in their opinion regarding their taste in reading. What type of sampling is used?

Convenience

Cluster Sampling

Obtained by dividing the population into groups and selecting all individuals from within a random sample of the groups

Stratified sample

Obtained by dividing the population into homogeneous groups and randomly selecting individuals from each group.

What does it mean when sampling is done without replacement?

Once an individual is selected, the individual cannot be selected again.

Ford wants to administer a satisfaction survey to its current customers. Using their customer database, the company randomly selects 30 customers and asks them about their level of satisfaction with the company. What type of sampling is used?

Simple Random

Apple wants to administer a satisfaction survey to its current customers. Using their customer database, the company randomly selects 60 customers and asks them about their level of satisfaction with the company. What type of sampling is used?

Simple random

To determine her blood sugar level, Keri divides up her day into three parts: morning, afternoon, and evening. She then measures her blood sugar level at 4 randomly selected times during each part of the day. What type of sampling is used?

Stratified

To estimate the percentage of defects in a recent manufacturing batch, a quality control manager at Microsoft selects every 18th software CD that comes off the assembly line starting with the third until she obtains a sample of 90 software CDs. What type of sampling is used?

Systematic

TRUE/FALSE: Inferences based on voluntary response samples are generally not reliable.

TRUE: because it is often the case that the individuals who volunteer do not accurately represent the population.