A researcher in the West Coast of the U.S. w

1.       A researcher in the West Coast of the U.S. wants to estimate the amount of a newly discovered antibody in human blood. His research funds will only let him obtain blood samples from 41 people, so he decides to construct a two-sided 90% confidence interval thinking it will give him a more precise estimate of the mean antibody level in the population. Another researcher on the East Coast of the United States is researching the same antibody, but has more research funding and can afford to obtain blood samples from 121 people. The East Coast researcher decides to construct a two-sided 99% confidence interval. Which researcher will have the more precise estimate?  State your reason for choosing your answer. It may help to imagine that the sample standard deviation will be about the same for both samples.

2.      Identify a pair of variables for which you would expect to see a strong correlation but not a cause-and-effect relationship. Suggest an explanation for the association.

3.      Twenty years ago, postal employees worked for the postal service an average of 7.5 years. Recently, a sample of 100 postal employees revealed that the average time these employees had worked for the postal service was () = 7 years. The population of employee lengths of service has a standard deviation = 5 years. Has  decreased from the mean of 7.5 years of 20 years ago? Conduct a hypothesis test (use H0:  µ =7.5). Use a .05 significance level. Is this evidence that the average length of employment with the postal service has decreased from twenty years ago?

4.      The salaries of the CEOs and the stock prices of 24 companies are shown in this scatterplot. A CEO uses this relation to argue there is a positive correlation between CEO salary and the Stock Price, and therefore, for the good sake of the company's stock value, his salary should be increased. Do you agree with his argument? Explain why or why not.

Dr. Hanson's mother Sally and her sister Pat have a rivalry about who makes the better apple pie. Sally makes two pies and has 16 people selected at random from her church eat a piece of pie and rate her pies on a scale of 1-10. The 16 ratings are as follows: 6, 8, 3, 9, 9, 9, 8, 8, 6, 7, 8, 7, 6, 7, 6, 8. Her sister Pat had 15 randomly selected people try a piece of pie at her church and the ratings were:7, 3, 9, 9, 8, 6, 6, 6, 7, 4, 8, 6, 10, 2, 7.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      

5.      Use the SPSS output to determine if there is sufficient evidence to conclude that Sally bakes a better pie than Pat (i.e., the average rating for Sally at her church is higher than the average rating for Pat at her church). Justify your conclusion.

6.      A nutritionist thinks the average person with an income below the poverty level gets less than the recommended daily allowance (RDA) of 800 mg of calcium. To test her conjecture, she obtains the daily intakes of calcium for a random sample of 45 people with incomes below the poverty level. The mean of the sample is 737.3 mg with sample standard deviation of 262.2 mg. Is there sufficient evidence at the alpha =0.05 level to support the researcher's claim?

7.      Shown below are the results of a one sample t test. Make up a problem that someone could solve using the printout. Do not make up the data. Just assume the data were collected and produced the given statistics.

8. Suppose you want to determine whether students' expected grades at the beginning of an introduction to statistics course are positively related to their final course grade. Write the null and alternative hypotheses in words.

Ten states were randomly selected from among the 50 United States. This data set  presents the percentage of households in each state that were below the poverty level (Poverty Rate) and the percentage of adults in the state who had earned a high school degree or higher (HS and Above). In the table is the mean and standard deviation for each variable, and the correlation for the two variables. You do not need to calculate these values.

9.      One of the points is suspected of being a bivariate outlier. When this point is removed, the new correlation is r = -.833. Is this point likely to be a bivariate outlier? Explain your answer.

The following stemplot represents the yearly percentage increases in Dickinson's comprehensive fees over the past 22 years. (3 | 8 means that one year had a percentage increase of 3.8%.)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             &n