Intro Stats
4th Edition
ISBN: 9780321825278
Author: Richard D. De Veaux, Paul F. Velleman, David E. Bock
Publisher: PEARSON
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Chapter 6, Problem 25E
Streams and hard water In a study of streams in the Adirondack Mountains, the following relationship was found between the water’s pH and its hardness (measured in grains):
Is it appropriate to summarize the strength of association with a
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A marketing professor has surveyed the students at her university to better understand attitudes towards PPT usage for higher education. To be able to make inferences to the entire student body, the sample drawn needs to represent the university’s student population on all key characteristics. The table below shows the five key student demographic variables. The professor found the breakdown of the overall student body in the university’s fact book posted online.
A non-parametric chi-square test was used to test the sample demographics against the population percentages shown in the table above. Review the output for the five chi-square tests on the following pages and answer the five questions:
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A marketing professor has surveyed the students at her university to better understand attitudes towards PPT usage for higher education. To be able to make inferences to the entire student body, the sample drawn needs to represent the university’s student population on all key characteristics. The table below shows the five key student demographic variables. The professor found the breakdown of the overall student body in the university’s fact book posted online.
A non-parametric chi-square test was used to test the sample demographics against the population percentages shown in the table above. Review the output for the five chi-square tests on the following pages and answer the five questions:
Based on the chi-square test, which sample variables adequately represent the university’s student population and which ones do not? Support your answer by providing the p-value of the chi-square test and explaining what it means.
Using the results from Question 1, make recommendation for…
A retail chain is interested in determining whether a digital video point-of-purchase (POP) display would stimulate higher sales for a brand advertised compared to the standard cardboard point-of-purchase display. To test this, a one-shot static group design experiment was conducted over a four-week period in 100 different stores. Fifty stores were randomly assigned to the control treatment (standard display) and the other 50 stores were randomly assigned to the experimental treatment (digital display). Compare the sales of the control group (standard POP) to the experimental group (digital POP).
What were the average sales for the standard POP display (control group)?
What were the sales for the digital display (experimental group)?
What is the (mean) difference in sales between the experimental group and control group?
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Chapter 6 Solutions
Intro Stats
Ch. 6.2 - Your statistics instructor tells you that the...Ch. 6.2 - Your statistics instructor tells you that the...Ch. 6.2 - Your statistics instructor tells you that the...Ch. 6.2 - Prob. 4JCCh. 6.2 - Prob. 5JCCh. 6 - Association Suppose you were to collect data for...Ch. 6 - Association II Suppose you were to collect data...Ch. 6 - Bookstore sales Consider the following data from a...Ch. 6 - Prob. 4ECh. 6 - Prob. 5E
Ch. 6 - Correlation facts II If we assume that the...Ch. 6 - Prob. 7ECh. 6 - Prob. 8ECh. 6 - Prob. 9ECh. 6 - Prob. 10ECh. 6 - Association III Suppose you were to collect data...Ch. 6 - Prob. 12ECh. 6 - Prob. 13ECh. 6 - Prob. 14ECh. 6 - Prob. 15ECh. 6 - Prob. 16ECh. 6 - Firing pottery A ceramics factory can fire eight...Ch. 6 - Coffee sales Owners of a new coffee shop tracked...Ch. 6 - Matching Here are several scatterplots. The...Ch. 6 - Matching II Here are several scatterplots. The...Ch. 6 - Prob. 21ECh. 6 - Car thefts The National Insurance Crime Bureau...Ch. 6 - Prob. 23ECh. 6 - Antidepressants A study compared the effectiveness...Ch. 6 - Streams and hard water In a study of streams in...Ch. 6 - Traffic headaches A study of traffic delays in 68...Ch. 6 - Cold nights Is there an association between time...Ch. 6 - Association V A researcher investigating the...Ch. 6 - Prob. 29ECh. 6 - Prob. 30ECh. 6 - Correlation errors Your Economics instructor...Ch. 6 - More correlation errors Students in the Economics...Ch. 6 - Height and reading A researcher studies children...Ch. 6 - Prob. 34ECh. 6 - Correlation conclusions I The correlation between...Ch. 6 - Prob. 36ECh. 6 - Prob. 37ECh. 6 - Sample survey A polling organization is checking...Ch. 6 - Income and housing The Office of Federal Housing...Ch. 6 - Prob. 40ECh. 6 - 41. Fuel economy 2010 Here are advertised...Ch. 6 - Drug abuse A survey was conducted in the United...Ch. 6 - Prob. 43ECh. 6 - Burgers again In the previous exercise you...Ch. 6 - Prob. 45ECh. 6 - 46. Second inning 2010 Perhaps fans are just more...Ch. 6 - Prob. 47ECh. 6 - Prob. 48ECh. 6 - Prob. 49ECh. 6 - Vehicle weights The Minnesota Department of...Ch. 6 - Prob. 51ECh. 6 - Prob. 52E
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- - + ++ Table 2: Crack Experiment for Exercise 2 A B C D Treatment Combination (1) Replicate I II 7.037 6.376 14.707 15.219 |++++ 1 བྱ॰༤༠སྦྱོ སྦྱོཋཏྟཱུ a b ab 11.635 12.089 17.273 17.815 с ас 10.403 10.151 4.368 4.098 bc abc 9.360 9.253 13.440 12.923 d 8.561 8.951 ad 16.867 17.052 bd 13.876 13.658 abd 19.824 19.639 cd 11.846 12.337 acd 6.125 5.904 bcd 11.190 10.935 abcd 15.653 15.053 Question 3 Continuation of Exercise 2. One of the variables in the experiment described in Exercise 2, heat treatment method (C), is a categorical variable. Assume that the remaining factors are continuous. (a) Write two regression models for predicting crack length, one for each level of the heat treatment method variable. What differences, if any, do you notice in these two equations? (b) Generate appropriate response surface contour plots for the two regression models in part (a). (c) What set of conditions would you recommend for the factors A, B, and D if you use heat treatment method C = +? (d) Repeat…arrow_forwardQuestion 2 A nickel-titanium alloy is used to make components for jet turbine aircraft engines. Cracking is a potentially serious problem in the final part because it can lead to nonrecoverable failure. A test is run at the parts producer to determine the effect of four factors on cracks. The four factors are: pouring temperature (A), titanium content (B), heat treatment method (C), amount of grain refiner used (D). Two replicates of a 24 design are run, and the length of crack (in mm x10-2) induced in a sample coupon subjected to a standard test is measured. The data are shown in Table 2. 1 (a) Estimate the factor effects. Which factor effects appear to be large? (b) Conduct an analysis of variance. Do any of the factors affect cracking? Use a = 0.05. (c) Write down a regression model that can be used to predict crack length as a function of the significant main effects and interactions you have identified in part (b). (d) Analyze the residuals from this experiment. (e) Is there an…arrow_forwardA 24-1 design has been used to investigate the effect of four factors on the resistivity of a silicon wafer. The data from this experiment are shown in Table 4. Table 4: Resistivity Experiment for Exercise 5 Run A B с D Resistivity 1 23 2 3 4 5 6 7 8 9 10 11 12 I+I+I+I+Oooo 0 0 ||++TI++o000 33.2 4.6 31.2 9.6 40.6 162.4 39.4 158.6 63.4 62.6 58.7 0 0 60.9 3 (a) Estimate the factor effects. Plot the effect estimates on a normal probability scale. (b) Identify a tentative model for this process. Fit the model and test for curvature. (c) Plot the residuals from the model in part (b) versus the predicted resistivity. Is there any indication on this plot of model inadequacy? (d) Construct a normal probability plot of the residuals. Is there any reason to doubt the validity of the normality assumption?arrow_forward
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