Question 1: The data in DJIA.xls represent the closing values of the Dow Jones Industrial Average (DJIA) from 1979 through 2008.
a) Plot the time series.
b) Find a three-years moving average to the data and plot the results.
c) Using a smoothing coefficient of W = 0.50, exponentially smooth the series and plot the results.
Question 2:Refer to the data set given in [1].
a) Compute a linear trend forecasting equation and plot the trend line.
b) Compute a quadratic trend forecasting equation and plot the results.
c) Compute an exponential trend forecasting equation and plot the results.
d) Which model is the most appropriate, using adjusted r2 values and first, second, and percentage differences.
Question 3: Refer to the data set given in [1].
a) Fit a third-order autoregressive model to the DJIA and test for the significance of the third-order autoregressive parameter using a = 0.05.
b) If necessary, fit a second-order autoregressive model to the DJIA and test for the significance of the second-order autoregressive parameter using a = 0.05.
c) If necessary, fit a first-order autoregressive model to the DJIA and test for the significance of the first-order autoregressive parameter using a = 0.05.
d) Using the most appropriate model in a) - c), forecast the closing values for 2009 and 2010.
Question 4: A study was conducted of the association between intoxication and pedestrian deaths, with the results shown in the accompanying table (based on data from the National Highway Traffic Safety Administration). Use a 0.05 significance level to test the claim that pedestrian fatalities are independent of the intoxication of the driver and the intoxication of the pedestrian.
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Pedestrian Intoxicated
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Pedestrian Not Intoxicated
|
|
Driver intoxicated
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59
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79
|
|
Driver not intoxicated
|
266
|
581
|
Question 5:Use the data in the table to test the claim that occupation is independent of whether the cause of death was homicide. The table is based on data from the U.S. Department of Labor, Bureau of Labor Statistics. Does any particular occupation appear to be most prone to homicide? If so, which one?
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Police
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Cashiers
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Taxi Drivers
|
Guards
|
|
Homicide
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82
|
107
|
70
|
59
|
|
Cause of death other than homicide
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92
|
9
|
29
|
42
|
Question 6: Based on data from a Gallup poll, the following table summarizes results from a survey of workers and senior-level bosses who were asked if it was seriously unethical to monitor employee e-mail.
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Workers
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Bosses
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Yes
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192
|
40
|
|
No
|
244
|
81
|
Use a 0.05 significance level to test the claim that response is independent of whether the person is a worker or senior-level boss.
Question 7: The table summarizes results from a clinical trial (based on data from Pfizer, Inc). Use a 0.05 significance level to test the claim that experiencing nausea is independent of whether a subject is treated with Celebrex, Ibuprofen, or a placebo. Does the adverse reaction of nausea appear to be about the same for the different treatments?
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Celebrex
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Ibuprofen
|
Placebo
|
|
Nausea
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145
|
23
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78
|
|
No Nausea
|
4001
|
322
|
1786
|
Question 8: A Pew Research poll was conducted to investigate opinions about global warming. The respondents who answered yes when asked if there is solid evidence that the earth is getting warmer were then asked to select a cause of global warming. The results for two age brackets are given in the table. Use a 0.01 significance level to test the claim that the age bracket is independent of the choice for the cause of global warming. Do respondents from both age brackets appear to agree, or is there a substantial difference?
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Human activity
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Natural patterns
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Don't know or refused answer
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Under 30
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108
|
41
|
7
|
|
65 and over
|
121
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71
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43
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Question 9: In an article in Marketing Science, Silk and Berndt investigate the output of advertising agencies. They describe ad agency output by finding the shares of dollar billing volume coming from various media categories such as network television, spot television, newspaper, radio, and so forth.
a) Suppose that a random sample of 400 U.S. advertising agencies gives an average percentage share of billing volume from network television equal to 7.46 percent with a standard deviation of 1.42 percent. Calculate a 95 percent confidence interval for the mean percentage share of billing volume from network television for the population of all U.S. advertising agencies.
b) Suppose that a random sample of 400 U.S. advertising agencies gives an average percentage share of billing volume from spot television commercials equal to 12.44 percent with a standard deviation of 1.55 percent. Calculate a 95 percent confidence interval for the mean percentage share of billing volume from spot television commercials for the population of all U.S. advertising agencies.
c) Compare the confidence intervals in part a) and b). Does it appear that the mean percentage share of billing volume from spot television commercials for the U.S. advertising agencies is greater than the mean percentage share of billing volume from network television? Explain.
Question 10: In the case of Castenedav. Partida, it was found that during a period of 11 years in Hilda County, Texas, 870 people were selected for grand jury duty, and 39% of them were Americans of Mexican ancestry. Among the people eligible for grand jury duty, 79.1% were Americans of Mexican ancestry. We want to determine ifthe selection process is biased against Americans of Mexican ancestry or not.
a) Construct a 98% confidence interval estimate of the proportion of Americans of Mexican ancestry selected for grand jury during a period of 11 years.
b) Does the jury selection system appear to be fair?