Exam 1: Introduction to Statistics

A stock analyst compares the relationship between stock prices and earnings per share to help him select a stock for investment.

Identify which type of sampling is used. A research team wants to study the demographics of college students in the United States using proportionate samples of students in majors reflecting actual U.S. percentages.

An education expert is researching teaching methods and wishes to interview teachers from a particular school district. She randomly selects ten schools from the district and interviews all of the teachers at the selected Schools. Does this sampling plan result in a random sample? Simple random sample? Explain.

The temperatures of eight different plastic spheres.

Determine which level of measurement is appropriate. Salaries of college professors.

You plan to make a survey of 200 people. The plan is to talk to every 10th person coming out of the school library. Is there a problem with your plan?

The table shows the weights (in pounds) and monthly incomes (in dollars) of nine randomly selected women between the ages of 18 and 65. Weight (lb) 113 132 155 122 166 140 118 129 185 Monthly Income (dollars) 1420 3650 5475 2310 4710 2910 1720 2460 4115 If we use statistical methods to conclude that there is a correlation (or relationship or association) between the weights of women and their monthly incomes, can we conclude that by increasing her weight a woman can increase her monthly income?

Identify which of these types of sampling is used: random, stratified, systematic, cluster, convenience. -A sample consists of every 49th student from a group of 496 students.

The subjects in which college students major.

After taking the first exam, 15 of the students dropped the class.

Provide an appropriate response. -A polling company obtains an alphabetical list of names of voters in a precinct. They select every 20th person from the list until a sample of 100 is obtained. They then call these 100 people. Does this sampling plan result in A random sample? Simple random sample? Explain.

The total number of phone calls a sales representative makes in a month is 425.

Identify the type of observational study (cross-sectional, retrospective, prospective). -A researcher plans to obtain data by following those in cancer remission since January of 2005.

A lawyer surveyed a simple random sample of his colleagues and asked them whether they were left-handed or right-handed. Is this convenience sample likely to provide results typical of all adults in the United States? Do convenience samples in general provide good results?

Identify the type of observational study (cross-sectional, retrospective, prospective). -A statistical analyst obtains data about ankle injuries by examining a hospital's records from the past 3 years.

The weight of Bill's pack as he sets off on a backpacking trip is 48.3 lb.

The height of 2-year-old maple tree is 28.3 ft.

A health and fitness club surveys 40 randomly selected members and found that the average weight of those questioned is 157 lb.

Identify which of these types of sampling is used: random, stratified, systematic, cluster, convenience. -A researcher interviews 19 work colleagues who work in his building.

Provide an appropriate response. -The personnel manager at a company wants to investigate job satisfaction among the female employees. One evening after a meeting she talks to all 30 female employees who attended the meeting. Does this sampling plan Result in a random sample? Simple random sample? Explain.