In: Math
perform Levene’s test for equal variance. Note, this is a one‐way ANOVA testing for the equality of 16 variances (each combination of promotion/discount). 0.1 signigicance
2. perform 2-way anova with replication
To answer these questions, an experiment was designed using laundry detergent pods. For ten weeks, 160 subjects received information about the products. The factors under consideration were the number of promotions (1, 3, 5, or 7) that were described during this ten‐ week period and the percent that the product was discounted (10%, 20%, 30%, or 40%) off the average non‐promotional price. Ten individuals were randomly assigned to each of the sixteen combinations. The data reflecting what the sub‐ jects would expect to pay for the product (i.e., their reference price) at the end of the 10‐week period. 0.1 significance
Stop 'N Shop Reference Pricing Data | Note: the headings reflect the number of promotions and the percent discount | Stop 'N Shop Case.xlsx | |||||||||||||
(for example: N5D30 represents 5 promotions with a 30 percent discount). | |||||||||||||||
N1D10 | N3D10 | N5D10 | N7D10 | N1D20 | N3D20 | N5D20 | N7D20 | N1D30 | N3D30 | N5D30 | N7D30 | N1D40 | N3D40 | N5D40 | N7D40 |
11.36 | 11.33 | 11.15 | 10.82 | 10.83 | 11.46 | 11.16 | 10.71 | 12.20 | 12.14 | 11.37 | 11.15 | 12.45 | 12.16 | 11.57 | 11.30 |
11.76 | 11.39 | 11.44 | 11.17 | 11.03 | 11.20 | 11.03 | 11.32 | 11.85 | 12.06 | 11.61 | 11.71 | 12.14 | 12.41 | 11.62 | 11.48 |
11.73 | 11.51 | 11.08 | 11.31 | 11.16 | 11.46 | 11.12 | 10.61 | 11.84 | 11.72 | 11.43 | 11.06 | 12.04 | 11.94 | 12.01 | 11.65 |
11.68 | 11.49 | 11.35 | 11.17 | 11.75 | 11.14 | 11.36 | 10.93 | 11.74 | 11.99 | 11.37 | 11.41 | 12.15 | 12.24 | 11.88 | 11.15 |
11.82 | 11.83 | 11.20 | 11.37 | 11.26 | 11.61 | 11.36 | 11.00 | 11.81 | 11.22 | 11.28 | 11.67 | 11.95 | 11.92 | 11.00 | 11.52 |
11.95 | 11.59 | 11.67 | 10.87 | 11.92 | 11.25 | 11.07 | 11.06 | 11.79 | 11.68 | 11.67 | 11.01 | 12.22 | 11.72 | 11.60 | 11.67 |
11.68 | 11.43 | 11.40 | 10.98 | 11.74 | 11.27 | 11.23 | 11.16 | 11.85 | 11.56 | 11.74 | 11.24 | 12.26 | 11.96 | 11.78 | 11.65 |
11.43 | 11.73 | 11.41 | 10.95 | 11.90 | 11.48 | 10.93 | 11.34 | 11.92 | 11.94 | 11.02 | 11.33 | 12.19 | 11.63 | 11.63 | 11.78 |
11.57 | 11.86 | 11.32 | 11.05 | 11.57 | 10.96 | 11.31 | 10.78 | 11.99 | 11.71 | 11.92 | 11.47 | 12.36 | 11.95 | 11.66 | 11.13 |
11.85 | 11.28 | 11.16 | 10.71 | 11.69 | 11.74 | 10.93 | 11.29 | 12.50 | 11.82 | 11.70 | 11.49 | 12.04 | 12.23 | 11.78 | 11.96 |
1)
The Levene’s Test for Equality of Variances for each combination of promotion and discount is performed in excel by following these steps,
Step 1: Write down the data values for each 16 group. The screenshot is shown below,
Step 2: Calculate the standard deviation for each group using the excel function =STEDEV(). Now, the variance is obtained by taking square of standard deviation.
Step 3: The null and alternative hypothesis are,
Step 4: The F-value is obtained using the formula,
and the corresponding P-value is obtained using the excel function =F.DIST(x,deg_freedom1,deg_freedom2,TRUE)
Step 5: The significance level is 0.01 such that the null hypothesis is rejected if,
P-value < 0.01
Combination | |||||||
Group 1 | Group 2 | s1^2 | s2^2 | F=s1^2/s2^2 | P-value | ||
1 | 1 | 2 | 0.0341 | 0.0416 | 0.8200 | 0.3862 | FALSE |
2 | 1 | 3 | 0.0341 | 0.0310 | 1.1021 | 0.5564 | FALSE |
3 | 1 | 4 | 0.0341 | 0.0460 | 0.7428 | 0.3325 | FALSE |
4 | 1 | 5 | 0.0341 | 0.1487 | 0.2296 | 0.0196 | FALSE |
5 | 1 | 6 | 0.0341 | 0.0550 | 0.6201 | 0.2438 | FALSE |
6 | 1 | 7 | 0.0341 | 0.0265 | 1.2865 | 0.6432 | FALSE |
7 | 1 | 8 | 0.0341 | 0.0685 | 0.4981 | 0.1569 | FALSE |
8 | 1 | 9 | 0.0341 | 0.0543 | 0.6284 | 0.2499 | FALSE |
9 | 1 | 10 | 0.0341 | 0.0733 | 0.4657 | 0.1352 | FALSE |
10 | 1 | 11 | 0.0341 | 0.0701 | 0.4866 | 0.1491 | FALSE |
11 | 1 | 12 | 0.0341 | 0.0580 | 0.5889 | 0.2212 | FALSE |
12 | 1 | 13 | 0.0341 | 0.0231 | 1.4770 | 0.7147 | FALSE |
13 | 1 | 14 | 0.0341 | 0.0590 | 0.5785 | 0.2137 | FALSE |
14 | 1 | 15 | 0.0341 | 0.0721 | 0.4734 | 0.1402 | FALSE |
15 | 1 | 16 | 0.0341 | 0.0729 | 0.4685 | 0.1370 | FALSE |
16 | 2 | 3 | 0.0416 | 0.0310 | 1.3440 | 0.6666 | FALSE |
17 | 2 | 4 | 0.0416 | 0.0460 | 0.9058 | 0.4426 | FALSE |
18 | 2 | 5 | 0.0416 | 0.1487 | 0.2799 | 0.0358 | FALSE |
19 | 2 | 6 | 0.0416 | 0.0550 | 0.7562 | 0.3420 | FALSE |
20 | 2 | 7 | 0.0416 | 0.0265 | 1.5688 | 0.7436 | FALSE |
21 | 2 | 8 | 0.0416 | 0.0685 | 0.6074 | 0.2346 | FALSE |
22 | 2 | 9 | 0.0416 | 0.0543 | 0.7663 | 0.3491 | FALSE |
23 | 2 | 10 | 0.0416 | 0.0733 | 0.5679 | 0.2061 | FALSE |
24 | 2 | 11 | 0.0416 | 0.0701 | 0.5935 | 0.2245 | FALSE |
25 | 2 | 12 | 0.0416 | 0.0580 | 0.7182 | 0.3149 | FALSE |
26 | 2 | 13 | 0.0416 | 0.0231 | 1.8012 | 0.8031 | FALSE |
27 | 2 | 14 | 0.0416 | 0.0590 | 0.7055 | 0.3058 | FALSE |
28 | 2 | 15 | 0.0416 | 0.0721 | 0.5772 | 0.2128 | FALSE |
29 | 2 | 16 | 0.0416 | 0.0729 | 0.5714 | 0.2085 | FALSE |
30 | 3 | 4 | 0.0310 | 0.0460 | 0.6740 | 0.2830 | FALSE |
31 | 3 | 5 | 0.0310 | 0.1487 | 0.2083 | 0.0143 | FALSE |
32 | 3 | 6 | 0.0310 | 0.0550 | 0.5627 | 0.2023 | FALSE |
33 | 3 | 7 | 0.0310 | 0.0265 | 1.1673 | 0.5893 | FALSE |
34 | 3 | 8 | 0.0310 | 0.0685 | 0.4519 | 0.1262 | FALSE |
35 | 3 | 9 | 0.0310 | 0.0543 | 0.5702 | 0.2077 | FALSE |
36 | 3 | 10 | 0.0310 | 0.0733 | 0.4226 | 0.1078 | FALSE |
37 | 3 | 11 | 0.0310 | 0.0701 | 0.4416 | 0.1196 | FALSE |
38 | 3 | 12 | 0.0310 | 0.0580 | 0.5344 | 0.1822 | FALSE |
39 | 3 | 13 | 0.0310 | 0.0231 | 1.3402 | 0.6651 | FALSE |
40 | 3 | 14 | 0.0310 | 0.0590 | 0.5249 | 0.1755 | FALSE |
41 | 3 | 15 | 0.0310 | 0.0721 | 0.4295 | 0.1120 | FALSE |
42 | 3 | 16 | 0.0310 | 0.0729 | 0.4251 | 0.1093 | FALSE |
43 | 4 | 5 | 0.0460 | 0.1487 | 0.3091 | 0.0476 | FALSE |
44 | 4 | 6 | 0.0460 | 0.0550 | 0.8349 | 0.3962 | FALSE |
45 | 4 | 7 | 0.0460 | 0.0265 | 1.7320 | 0.7872 | FALSE |
46 | 4 | 8 | 0.0460 | 0.0685 | 0.6706 | 0.2805 | FALSE |
47 | 4 | 9 | 0.0460 | 0.0543 | 0.8460 | 0.4037 | FALSE |
48 | 4 | 10 | 0.0460 | 0.0733 | 0.6270 | 0.2489 | FALSE |
49 | 4 | 11 | 0.0460 | 0.0701 | 0.6552 | 0.2694 | FALSE |
50 | 4 | 12 | 0.0460 | 0.0580 | 0.7929 | 0.3676 | FALSE |
51 | 4 | 13 | 0.0460 | 0.0231 | 1.9885 | 0.8398 | FALSE |
52 | 4 | 14 | 0.0460 | 0.0590 | 0.7788 | 0.3579 | FALSE |
53 | 4 | 15 | 0.0460 | 0.0721 | 0.6373 | 0.2563 | FALSE |
54 | 4 | 16 | 0.0460 | 0.0729 | 0.6308 | 0.2516 | FALSE |
55 | 5 | 6 | 0.1487 | 0.0550 | 2.7013 | 0.9225 | FALSE |
56 | 5 | 7 | 0.1487 | 0.0265 | 5.6041 | 0.9914 | FALSE |
57 | 5 | 8 | 0.1487 | 0.0685 | 2.1697 | 0.8680 | FALSE |
58 | 5 | 9 | 0.1487 | 0.0543 | 2.7373 | 0.9252 | FALSE |
59 | 5 | 10 | 0.1487 | 0.0733 | 2.0288 | 0.8466 | FALSE |
60 | 5 | 11 | 0.1487 | 0.0701 | 2.1199 | 0.8608 | FALSE |
61 | 5 | 12 | 0.1487 | 0.0580 | 2.5655 | 0.9117 | FALSE |
62 | 5 | 13 | 0.1487 | 0.0231 | 6.4339 | 0.9947 | FALSE |
63 | 5 | 14 | 0.1487 | 0.0590 | 2.5201 | 0.9076 | FALSE |
64 | 5 | 15 | 0.1487 | 0.0721 | 2.0620 | 0.8520 | FALSE |
65 | 5 | 16 | 0.1487 | 0.0729 | 2.0410 | 0.8486 | FALSE |
66 | 6 | 7 | 0.0550 | 0.0265 | 2.0746 | 0.8540 | FALSE |
67 | 6 | 8 | 0.0550 | 0.0685 | 0.8032 | 0.3747 | FALSE |
68 | 6 | 9 | 0.0550 | 0.0543 | 1.0133 | 0.5077 | FALSE |
69 | 6 | 10 | 0.0550 | 0.0733 | 0.7510 | 0.3383 | FALSE |
70 | 6 | 11 | 0.0550 | 0.0701 | 0.7848 | 0.3620 | FALSE |
71 | 6 | 12 | 0.0550 | 0.0580 | 0.9497 | 0.4700 | FALSE |
72 | 6 | 13 | 0.0550 | 0.0231 | 2.3818 | 0.8939 | FALSE |
73 | 6 | 14 | 0.0550 | 0.0590 | 0.9329 | 0.4596 | FALSE |
74 | 6 | 15 | 0.0550 | 0.0721 | 0.7633 | 0.3470 | FALSE |
75 | 6 | 16 | 0.0550 | 0.0729 | 0.7556 | 0.3415 | FALSE |
76 | 7 | 8 | 0.0265 | 0.0685 | 0.3872 | 0.0868 | FALSE |
77 | 7 | 9 | 0.0265 | 0.0543 | 0.4885 | 0.1504 | FALSE |
78 | 7 | 10 | 0.0265 | 0.0733 | 0.3620 | 0.0731 | FALSE |
79 | 7 | 11 | 0.0265 | 0.0701 | 0.3783 | 0.0819 | FALSE |
80 | 7 | 12 | 0.0265 | 0.0580 | 0.4578 | 0.1300 | FALSE |
81 | 7 | 13 | 0.0265 | 0.0231 | 1.1481 | 0.5798 | FALSE |
82 | 7 | 14 | 0.0265 | 0.0590 | 0.4497 | 0.1248 | FALSE |
83 | 7 | 15 | 0.0265 | 0.0721 | 0.3679 | 0.0762 | FALSE |
84 | 7 | 16 | 0.0265 | 0.0729 | 0.3642 | 0.0742 | FALSE |
85 | 8 | 9 | 0.0685 | 0.0543 | 1.2616 | 0.6326 | FALSE |
86 | 8 | 10 | 0.0685 | 0.0733 | 0.9351 | 0.4610 | FALSE |
87 | 8 | 11 | 0.0685 | 0.0701 | 0.9770 | 0.4865 | FALSE |
88 | 8 | 12 | 0.0685 | 0.0580 | 1.1824 | 0.5965 | FALSE |
89 | 8 | 13 | 0.0685 | 0.0231 | 2.9654 | 0.9395 | FALSE |
90 | 8 | 14 | 0.0685 | 0.0590 | 1.1615 | 0.5864 | FALSE |
91 | 8 | 15 | 0.0685 | 0.0721 | 0.9504 | 0.4704 | FALSE |
92 | 8 | 16 | 0.0685 | 0.0729 | 0.9407 | 0.4645 | FALSE |
93 | 9 | 10 | 0.0543 | 0.0733 | 0.7411 | 0.3313 | FALSE |
94 | 9 | 11 | 0.0543 | 0.0701 | 0.7744 | 0.3548 | FALSE |
95 | 9 | 12 | 0.0543 | 0.0580 | 0.9372 | 0.4623 | FALSE |
96 | 9 | 13 | 0.0543 | 0.0231 | 2.3504 | 0.8905 | FALSE |
97 | 9 | 14 | 0.0543 | 0.0590 | 0.9206 | 0.4520 | FALSE |
98 | 9 | 15 | 0.0543 | 0.0721 | 0.7533 | 0.3399 | FALSE |
99 | 9 | 16 | 0.0543 | 0.0729 | 0.7456 | 0.3345 | FALSE |
100 | 10 | 11 | 0.0733 | 0.0701 | 1.0449 | 0.5256 | FALSE |
101 | 10 | 12 | 0.0733 | 0.0580 | 1.2646 | 0.6339 | FALSE |
102 | 10 | 13 | 0.0733 | 0.0231 | 3.1713 | 0.9497 | FALSE |
103 | 10 | 14 | 0.0733 | 0.0590 | 1.2422 | 0.6240 | FALSE |
104 | 10 | 15 | 0.0733 | 0.0721 | 1.0164 | 0.5095 | FALSE |
105 | 10 | 16 | 0.0733 | 0.0729 | 1.0060 | 0.5035 | FALSE |
106 | 11 | 12 | 0.0701 | 0.0580 | 1.2102 | 0.6096 | FALSE |
107 | 11 | 13 | 0.0701 | 0.0231 | 3.0350 | 0.9432 | FALSE |
108 | 11 | 14 | 0.0701 | 0.0590 | 1.1888 | 0.5995 | FALSE |
109 | 11 | 15 | 0.0701 | 0.0721 | 0.9727 | 0.4839 | FALSE |
110 | 11 | 16 | 0.0701 | 0.0729 | 0.9628 | 0.4779 | FALSE |
111 | 12 | 13 | 0.0580 | 0.0231 | 2.5079 | 0.9065 | FALSE |
112 | 12 | 14 | 0.0580 | 0.0590 | 0.9823 | 0.4896 | FALSE |
113 | 12 | 15 | 0.0580 | 0.0721 | 0.8037 | 0.3751 | FALSE |
114 | 12 | 16 | 0.0580 | 0.0729 | 0.7956 | 0.3694 | FALSE |
115 | 13 | 14 | 0.0231 | 0.0590 | 0.3917 | 0.0894 | FALSE |
116 | 13 | 15 | 0.0231 | 0.0721 | 0.3205 | 0.0527 | FALSE |
117 | 13 | 16 | 0.0231 | 0.0729 | 0.3172 | 0.0512 | FALSE |
118 | 14 | 15 | 0.0590 | 0.0721 | 0.8182 | 0.3850 | FALSE |
119 | 14 | 16 | 0.0590 | 0.0729 | 0.8099 | 0.3793 | FALSE |
120 | 15 | 16 | 0.0721 | 0.0729 | 0.9898 | 0.4940 | FALSE |
We can see that null hypothesis is failed to reject for each combination at 1% significant level. Hence we can conclude that all the variance are equal at 1% significant level.
2)
The two factor ANOVA test is performed in excel by following these steps,
Step 1: Write down the dat avalues in excel. The screenshot is shown below,
Step 2: DATA > Data Analysis > Anova: Two Factor With Replication. The screenshot is shown below,
Step 3: Select the Input Range, Row per sample = 10, Alpha = 0.01 > OK. The screenshot is shown below,
The result is obtained. The screenshot is shown below,
We can see that,
P-value for both the factor is less than 0.01 at 1% significant level. Hence there is significant effect of both the factor. But there is no interaction between two factor (the P-value for interaction is > 0.01)
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