A particular cellular phone company has collected data on a sample of its customers. The data file
Question:
A particular cellular phone company has collected data on a sample of its customers. The data file contains data on over 2,000 customers. Each row contains the activity of a particular customer for a given time period, and the last column indicates whether the customer churned during this time period. The company is trying to learn everything it can to keep churning to a minimum.
You can help by solving the following problems and then, based on your analysis, presenting a report to the company with recommendations.
1. The company wonders whether the period a customer has been using the company's service (‘Account Length’) has anything to do with the churning.
a. Calculate a 95% confidence interval for the mean account length of all customers who churn from the company. Do the same for those who do not churn. Then, calculate a 95% confidence interval for the difference between these means.
b. Among all customers whose account length is below the median (101 months), calculate a 95% confidence interval for the proportion who does not churn. Do the same for the customers with account lengths above the median. Then, calculate a 95% confidence interval for the difference between these proportions.
Data:
Customer | Account Length | Day Minutes | Day Calls | Day Charge | Evening Minutes | Evening Calls | Evening Charge | Night Minutes | Night Calls | Night Charge | International Minutes | International Calls | International Charge | Customer Service Calls | Churn? |
1 | 111 | 214,3 | 118 | 36,43 | 208,5 | 76 | 17,72 | 182,4 | 98 | 8,21 | 12 | 2 | 3,24 | 1 | No |
2 | 127 | 239,8 | 107 | 40,77 | 128,9 | 121 | 10,96 | 249,9 | 110 | 11,25 | 11,3 | 5 | 3,05 | 1 | No |
3 | 63 | 207,6 | 96 | 35,29 | 229 | 112 | 19,47 | 162,6 | 131 | 7,32 | 13,3 | 2 | 3,59 | 1 | No |
4 | 81 | 130,1 | 117 | 22,12 | 196 | 61 | 16,66 | 139,3 | 123 | 6,27 | 11,4 | 5 | 3,08 | 0 | No |
5 | 49 | 266,3 | 90 | 45,27 | 207,8 | 117 | 17,66 | 205 | 98 | 9,23 | 14 | 2 | 3,78 | 2 | Yes |
6 | 16 | 209,5 | 89 | 35,62 | 172,8 | 85 | 14,69 | 94,1 | 102 | 4,23 | 8,8 | 4 | 2,38 | 1 | No |
7 | 103 | 185,4 | 105 | 31,52 | 197,6 | 126 | 16,8 | 147,1 | 110 | 6,62 | 14,5 | 4 | 3,92 | 2 | No |
8 | 74 | 262,3 | 114 | 44,59 | 198,9 | 96 | 16,91 | 165,9 | 90 | 7,47 | 6,6 | 5 | 1,78 | 3 | No |
9 | 41 | 202,9 | 97 | 34,49 | 153,8 | 104 | 13,07 | 113,5 | 92 | 5,11 | 9 | 3 | 2,43 | 3 | No |
10 | 93 | 328,1 | 106 | 55,78 | 151,7 | 89 | 12,89 | 303,5 | 114 | 13,66 | 8,7 | 3 | 2,35 | 1 | Yes |
11 | 150 | 214 | 117 | 36,38 | 192,4 | 89 | 16,35 | 242,6 | 99 | 10,92 | 7,9 | 4 | 2,13 | 1 | No |
12 | 64 | 228,6 | 88 | 38,86 | 248,5 | 109 | 21,12 | 167,1 | 124 | 7,52 | 9 | 1 | 2,43 | 3 | No |
13 | 99 | 169,2 | 70 | 28,76 | 271,5 | 77 | 23,08 | 170,2 | 104 | 7,66 | 10,6 | 2 | 2,86 | 0 | No |
14 | 75 | 122,8 | 89 | 20,88 | 211,3 | 104 | 17,96 | 261,4 | 91 | 11,76 | 10,7 | 2 | 2,89 | 2 | No |
15 | 189 | 208,3 | 106 | 35,41 | 236,7 | 123 | 20,12 | 179,1 | 120 | 8,06 | 11,3 | 5 | 3,05 | 3 | No |
16 | 130 | 213,1 | 105 | 36,23 | 206,2 | 108 | 17,53 | 163,4 | 93 | 7,35 | 8,9 | 3 | 2,4 | 0 | No |
17 | 81 | 115,3 | 99 | 19,6 | 224,7 | 117 | 19,1 | 152,5 | 98 | 6,86 | 18 | 2 | 4,86 | 1 | No |
18 | 182 | 69,1 | 114 | 11,75 | 230,3 | 109 | 19,58 | 256,7 | 96 | 11,55 | 6,5 | 4 | 1,76 | 0 | No |
19 | 78 | 162,3 | 116 | 27,59 | 192,4 | 86 | 16,35 | 240,6 | 100 | 10,83 | 10,1 | 3 | 2,73 | 2 | No |
20 | 128 | 125,2 | 99 | 21,28 | 205,4 | 107 | 17,46 | 254,4 | 111 | 11,45 | 18,9 | 2 | 5,1 | 0 | No |
21 | 116 | 205 | 90 | 34,85 | 140,9 | 114 | 11,98 | 272,6 | 96 | 12,27 | 7,5 | 4 | 2,03 | 2 | No |
22 | 54 | 214,1 | 77 | 36,4 | 240,5 | 94 | 20,44 | 188,9 | 75 | 8,5 | 10,1 | 3 | 2,73 | 1 | No |
23 | 30 | 162,3 | 96 | 27,59 | 244 | 122 | 20,74 | 180,1 | 89 | 8,1 | 9,1 | 4 | 2,46 | 2 | No |
24 | 107 | 260,5 | 108 | 44,29 | 102,4 | 110 | 8,7 | 129,7 | 148 | 5,84 | 9,8 | 5 | 2,65 | 1 | No |
25 | 106 | 133,7 | 45 | 22,73 | 187,8 | 107 | 15,96 | 181,9 | 89 | 8,19 | 10,7 | 2 | 2,89 | 1 | Yes |
26 | 166 | 175,8 | 126 | 29,89 | 253,6 | 76 | 21,56 | 128,5 | 72 | 5,78 | 11,4 | 5 | 3,08 | 1 | No |
27 | 85 | 212,3 | 107 | 36,09 | 228,4 | 103 | 19,41 | 163,3 | 116 | 7,35 | 7,7 | 3 | 2,08 | 0 | No |
28 | 95 | 184,2 | 95 | 31,31 | 181,6 | 101 | 15,44 | 143,4 | 113 | 6,45 | 12,8 | 4 | 3,46 | 2 | No |
29 | 4 | 145,3 | 89 | 24,7 | 303,8 | 93 | 25,82 | 206,1 | 82 | 9,27 | 8,9 | 4 | 2,4 | 0 | No |
Data Analysis and Decision Making
ISBN: 978-0538476126
4th edition
Authors: Christian Albright, Wayne Winston, Christopher Zappe