Sampling – Flashcard

Suppose you want to determine the musical preferences of all students at your university, based on a sample of students. Post a music-lovers' survey on a university internet bulletin board, asking students to vote for their favorite type of music.

Suppose you want to determine the musical preferences of all students at your university, based on a sample of students. Stand outside the Student Union, across from the Fine Arts Building, and ask students passing by to respond to your question about musical preference.

Ask your professors for email rosters of all the students in your classes. Randomly sample some addresses, and email those students with your question about musical preference.

Obtain a student directory with email addresses of all the university's students, and send the music poll to every 50th name on the list.

IF individuals are sampled completely at random, and without replacement, then each group of a given size is just as likely to be selected as all the other groups of that size.

you choose 3 high schools at random from among all the high schools in that city, and use all the high school seniors in the three selected high schools as your sample.

in order to get a random sample of high-school seniors from a certain city, we choose a random sample of 25 seniors from each of the high schools in that city.

Voters are selected at random from an alphabetical list of all registered voters.

Voters are selected by choosing at random several of the city's zip codes and selecting all the voters from those selected zip codes.

Several pieces of fruit from each tree in an orchard are selected.

An insurance industry research foundation wants to study the quality of care given to all patients at risk for heart disease in the United States. Since not all those at risk seek treatment, the foundation randomly selects 3,500 claims only from among those at-risk patients who were actually treated for chest pain. The foundation obtains this sample in several stages. First, the foundation identifies 5 large companies that represent a broad cross-section of patients, chooses 2 of the 5 at random, and gains access to the claims of all the companies' patients. The two companies' claims are classified (depending on their origin) to 7 geographical regions (California, Florida, Great Lakes, Midwest, Northeast, Southern, and Southwest), and within each region, 5 counties are selected that represent a continuum spanning rural, suburban, and urban populations. (In total, then, patients from 35 counties are included). Within each county (and for each company), claims of 25 male and 25 female patients treated for chest pain are randomly selected for the study, for a total of 3,500 patients.

The research foundation identifies 5 large companies that represent a broad cross-section of patients, chooses 2 of the 5 at random, and gains access to the claims of all the companies' patients.

The 2 companies' claims are classified (depending on their origin) according to 7 geographical regions, and within each region, the sampling continues.

From each region, 5 representative counties are selected. (In total, all the claims originating from 35 counties are examined.)

Within each county (and for each company), claims of 25 male and 25 female patients are randomly selected.

When conducting a survey, it is important to use a random sample:

In order to obtain a sample of undergraduate students in the world, a simple random sample of 10 countries is selected. From each of the selected countries, 10 colleges or universities are chosen at random. Finally, from each of these 100 colleges or universities, a simple random sample of 20 undergraduate students is selected. Thus, the final sample consists of 2,000 undergraduates. This is an example of:

The city council for a large city wanted to know what proportion of the residents thought fitness classes should be available to everyone. The research department offered to cooperate in conducting a survey, and a simple random sample of 500 voters was selected from all the registered voters in the city. A survey form was sent by mail to these 500 voters. In this case, the population of interest is:

In this case, the sampling frame is:

Ross Times, the student newspaper of Ross College, printed a "What do you think?" column feature discussing the parking situation on campus. To gather student opinion on parking, an editor for the paper stood at the entrance to the student union and gathered responses from students as they left. In all, 126 responses were collected. This is an example of:

Which of the following is an example of stratified sampling?

The faculty senate at a large university wanted to know what proportion of the employees thought the food services at the university are satisfactory. The statistics department offered to cooperate in conducting a survey, and a simple random sample of 100 faculty members was selected. A survey form was sent by email to these 100 employees. In this case, the population of interest is:

Ross Times, the student newspaper of Ross College, printed a "What do you think?" column feature asking: "Do you think that the college is doing enough to provide student parking?" Anyone could mail in a response or use the papers Web site to respond. In all, 126 answers were received. This is an example of:

The human resources department of a large bank wanted to assess the job satisfaction of the banks workers. The department chose four of the banks branches at random, and used all of the workers in those four branches as the subjects for the study.

A health educator wanted to study the sleeping habits of the undergraduate students in her university. For her study, the researcher chose a simple random sample of size 150 from each of the classes (150 freshman, 150 sophomores, 150 juniors, and 150 seniors), for a total of 600 sampled students.

The faculty senate at a large university wanted to know what proportion of the students thought foreign language classes should be required for everyone. The statistics department offered to cooperate in conducting a survey, and a simple random sample of 500 students was selected from all the students enrolled in statistics classes. A survey form was sent by email to these 500 students. In this case, the population of interest is:

Ross Times, the student newspaper of Ross College, printed a "What do you think?" column feature asking: "Do you think that the college is doing enough to provide student parking?" The newspaper's editor randomly selected from the registrars list of students and then gathered their opinions. In all, 126 responses were collected. This is an example of: