You have been asked to select a 10 per cent sample of firms from the sampling frame used for self-check question 7.3.
a. Select a 10 per cent systematic random sample and mark those firms selected for the sample on the sampling frame.
b. Calculate the average (mean) annual output in tens of thousands of pounds over the past year for your sample.
c. Given that the true average annual output is £6,608,900, why does systematic random provide such a poor estimate of the annual output in this case?

Data from in self-check question 7.3

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 1 to 100.

1 2 3 4 5 6 7 Output 10 21 57 22 149 23 205 24 163 25 1359 26 330 27 Output 7 92 105 157 214 1440 390 41 42 43 44 45 46 47 Output 29 61 84 62 97 63 265 64 187 65 1872 66 454 67 Output 39 81 73 82 161 83 275 84 170 85 1598 86 378 87 Output 55 66 165 301 161 1341 431