Exam 7: Data for Decisions

The executives of an accounting firm plan to survey a random sample of clients to determine how satisfied they are with the service they have received. Of the firm's 5412 regular clients, 500 are surveyed and 435 claim to be very satisfied with the service they have received. The sample is:

Can we eliminate variability in results of sampling? Why or why not?

A polling company surveys 200 people outside a county courthouse concerning tighter restrictions on smoking in public buildings. Their results indicate that 34% of those surveyed favor tighter restrictions. The actual proportion of county residents who favor tighter restrictions is 65%. The difference is most likely due to:

You must choose a simple random sample of 25 of the 314 members of your fly fishing club. How would you label the population in order to use a table of random digits to make your selection?

A survey is sent to 100 employees at a community hospital asking if they support a law requiring motorcycle riders to wear helmets. The results indicate 88% support the law. If the actual proportion of the community's residents who support the law is 72%, the difference is most likely a result of:

When variables have effects on the outcome which cannot be distinguished from each other, those variables are said to be:

When you estimate a population proportion by sample, quadrupling the sample size:

A recent survey of 536 employees of U.S. corporations determined that 84% of them feel that the executives who run their companies are ethical. Determine the 95% confidence interval for this survey.

A physical education researcher wishes to determine if walking every day affects the health of middle-aged men. The researcher randomly identifies 400 participants in two groups. Members of one group belong to a health club and walk on its track and members of the other do not. After two months, the researcher decides the group who walks daily is healthier and concludes that walking positively affects men's health. This conclusion is of questionable validity because:

A school principal is concerned with the increasing level of absenteeism in the school. A meeting of parents, teachers, and students is called at which the principal expresses her concern and describes an experimental program that will be instituted to try to curb absenteeism. After two months, absenteeism is down by 15%. Explain how confounding variables may have affected the results of the experiment.

A new stadium is being planned for the local professional football team. One of the proposed funding methods involves the allocation of tax monies to build the stadium. To determine the public opinion of this plan, the first 100 people entering the stadium for a game are surveyed. Explain why the results of this survey might not be valid.

The Gamma Community College athletic department tests two new logos for the college's athletic teams (call them Modern and Traditional) by showing them to a random sample of 100 Gamma students. Sixty of the 100 prefer Modern. Then the department repeats the test by drawing a new random sample of 100. Again, 60 prefer the Modern logo. Given that 1000 students attend Gamma, this result is:

You sample all 1000 people in the population of interest and find that $\hat { p }$ is 0.2. Why should you not use the margin of error formula to find a 95% confidence interval for p?

Explain the difference between a parameter and a statistic.

Beginning with line 104 of the random digits table above, select three individuals to receive a prize in a contest. 01 Anderson 06 Hall 11 Opus 16 Thompson 02 Butts 07 Hunsaker 12 Parson 17 Ubet 03 Calvin 08 Jones 13 Quayle 18 Watson 04 Ernest 09 Miller 14 Riley 19 Wilson 05 Gaynor 10 Norton 15 Stone 20 Ziggy

Statistical inference refers to methods for drawing conclusions about sample statistics based on the statistical knowledge on the population.

A polling company conducted a survey of voters to obtain data for a political campaign. They selected 3500 voters randomly from the 168,000 names on the voter registration lists of the county and found that 1372 intended to vote for candidate Doe. The 168,000 names represent:

A telephone survey calls 200 registered voters in Ward 8 and asks them which of two candidates for alderman, Sullivan or Mossman, they prefer. Sixty say Sullivan, 60 say Mossman, and 80 refuse to answer. What is the nonresponse rate?

A marketing department surveys 1500 shoppers and finds that 950 would visit a new store more often if it was open on Sunday evenings. What is the sample proportion in this survey?

Beginning with line 102 of the random digits table above, select three individuals from the list below to serve on a student affairs committee. 01 Crosby 06 Jones 11 Turner 16 Bush 02 Hunter 07 Smith 12 Baker 17 Thompson 03 Cooper 08 Davis 13 Wilson 18 Goodman 04 Grant 09 Ewing 14 Adams 19 Stevens 05 Riley 10 Doe 15 Hill 20 Williams