You have been asked to select a sample of manufacturing firms using the sampling frame below. This also lists the value of their annual output in tens of thousands of pounds over the past year. To help you in selecting your sample the firms have been numbered from 0 to 99. LO4 Output Output Output Output Output 0 1163 20 1072 40 1257 60 1300 80 1034 1 10 21 7 41 29 61 39 81 55 2 57 22 92 42 84 62 73 82 66 3 149 23 105 43 97 63 161 83 165 4 205 24 157 44 265 64 275 84 301 5 163 25 214 45 187 65 170 85 161 6 1359 26 1440 46 1872 66 1598 86 1341 7 330 27 390 47 454 67 378 87 431 8 2097 28 1935 48 1822 68 1634 88 1756 9 1059 29 998 49 1091 69 1101 89 907 10 1037 30 1298 50 1251 70 1070 90 1158 11 59 31 10 51 9 71 37 91 27 12 68 32 70 52 93 72 88 92 66 13 166 33 159 53 103 73 102 93 147 14 302 34 276 54 264 74 157 94 203 15 161 35 215 55 189 75 168 95 163 16 1298 36 1450 56 1862 76 1602 96 1339 17 329 37 387 57 449 77 381 97 429 18 2103 38 1934 58 1799 78 1598 98 1760 19 1061 39 1000 59 1089 79 1099 99 898 a Select two simple random samples, each of 20 firms, and mark those firms selected for each sample on the sampling frame.
b Describe and compare the pattern on the sampling frame of each of the samples selected.
c Calculate the average (mean) annual output in tens of thousands of pounds over the past year for each of the samples selected.
d Given that the true average annual output is £6 608 900, is there any bias in either of the samples selected?