1.) Sixty-four students in an introductory college economics class were asked how many credits they had earned in college, and how certain they were about their choice of major. Research question: At α = .01, is the degree of certainty independent of credits earned?
This question requires data regarding the answers of the two questions asked to the 64 students.
2.) A student team examined parked cars in four different suburban shopping malls. One hundred vehicles were examined in each location. Research question: At α = .05, does vehicle type vary by mall location? (Data are from a project by MBA students Steve Bennett, Alicia Morais, Steve Olson, and Greg Corda.)
This question requires the data collected by the student team.
3.) High levels of cockpit noise in an aircraft can damage the hearing of pilots who are exposed to this hazard for many hours. A Boeing 727 co-pilot collected 61 noise observations using a handheld sound meter. Noise level is defined as "Low" (under 88 decibels), "Medium" (88 to 91 decibels), or "High" (92 decibels or more). There are three flight phases (Climb, Cruise, Descent). Research question: At α = .05, is the cockpit noise level independent of flight phase?
This question requires data collected by the co-pilot.
4.) Can people really identify their favorite brand of cola? Volunteers tasted Coca-Cola Classic, Pepsi, Diet Coke, and Diet Pepsi, with the results shown below. Research question: At α = .05, is the correctness of the prediction different for the two types of cola drinkers? Could you identify your favorite brand in this kind of test? Since it is a 2 × 2 table, try also a two-tailed two-sample z test for π1 = π2 (see Chapter 10) and verify that z2 is the same as your chi-square statistic.Which test do you prefer? Why?
This question requires the data collected.
5.) Johnson's Service Center has devised three potential options available to preferred customers who redeem coupons and buy at least 10 gallons of fuel when they stop in. Option A is a flat 3 cents off each gallon. Option B is a combination of 2 cents off plus another $1 discount on the regular price of a $5 deluxe car wash. Option C is a $2 discount on the same $5 deluxe car wash but no reduction in the fuel purchase. The owner, Harold Johnson, ran each option on three different two-week trial periods and tracked daily sales receipts from those customers who redeemed their coupons. Results are shown in the table below:
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Option A
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Option B
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Option C
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$453
507
513
521
511
615
601
552
551
505
515
512
476
427
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$492
514
536
511
528
678
611
653
596
516
534
543
498
437
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$467
525
516
500
435
462
411
674
512
559
624
711
512
416
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State the null and alternate hypotheses to test for equal population means. (50%)
Let μ_1,μ_(2,) ? μ?_3 respectively denote the mean sales receipts of the three options.
Null hypothesis H0: μ_1=μ_2=μ_3 (the mean sales receipts of the three options are equal)
Alternative hypothesis μ_1,μ_(2,) ? μ?_3 are not all equal.( the at least one of the three population mean total returns is different from the others)
b) (50%) Below are the results from EXCEL of ANOVA of the data at the 0.05 level of significance. Do the sample data indicate the at least one of the three population mean total returns is different from the others? Why? (Explain using "F" and "Fcrit")
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Anova: Single Factor
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SUMMARY
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Groups
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Count
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Sum
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Average
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Variance
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Column 1
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14
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7259
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518.5
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2555.962
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Column 2
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14
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7647
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546.2143
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4340.335
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Column 3
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14
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7324
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523.1429
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8389.209
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ANOVA
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Source of Variation
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SS
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df
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MS
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F
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P-value
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F crit
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Between Groups
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6169
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2
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3084.5
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0.605377
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0.550917
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3.2381
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Within Groups
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198711.6
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39
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5095.168
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Total
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204880.6
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41
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