In: Statistics and Probability
The manager of an assembly process wants to determine whether or not the number of defective articles manufactured depends on the day of the week the articles are produced. She collected the following information. Is there sufficient evidence to reject the hypothesis that the number of defective articles is independent of the day of the week on which they are produced? Use α = 0.01.
Day of Week | M | Tu | W | Th | F |
Nondefective | 88 | 92 | 98 | 97 | 91 |
Defective | 11 | 7 | 3 | 3 | 8 |
(a) Find the test statistic. (Round your answer to two decimal
places.)
(ii) Find the p-value. (Round your answer to four decimal
places.)
(a) The test statistic = 8.09
(ii) p-value = 0.0883
Col 1 | Col 2 | Col 3 | Col 4 | Col 5 | Total | ||
Row 1 | Observed | 88 | 92 | 98 | 97 | 91 | 466 |
Expected | 92.64 | 92.64 | 94.51 | 93.57 | 92.64 | 466.00 | |
O - E | -4.64 | -0.64 | 3.49 | 3.43 | -1.64 | 0.00 | |
(O - E)² / E | 0.23 | 0.00 | 0.13 | 0.13 | 0.03 | 0.52 | |
Row 2 | Observed | 11 | 7 | 3 | 3 | 8 | 32 |
Expected | 6.36 | 6.36 | 6.49 | 6.43 | 6.36 | 32.00 | |
O - E | 4.64 | 0.64 | -3.49 | -3.43 | 1.64 | 0.00 | |
(O - E)² / E | 3.38 | 0.06 | 1.88 | 1.83 | 0.42 | 7.57 | |
Total | Observed | 99 | 99 | 101 | 100 | 99 | 498 |
Expected | 99.00 | 99.00 | 101.00 | 100.00 | 99.00 | 498.00 | |
O - E | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | |
(O - E)² / E | 3.61 | 0.07 | 2.01 | 1.95 | 0.45 | 8.09 | |
8.09 | chi-square | ||||||
4 | df | ||||||
.0883 | p-value |
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