EXAMPLE 3.24

Select an SRS of countries using random digits. To use Table B, we need a numeric label. We could create such a label by adding a column to the data file TTS containing the numbers 1 to 189. An alternative requiring less work would be to use the numbers in the leftmost part of the spreadsheet. Notice in Figure 3.7(a), for example, that there is a 1 in the first row of the spreadsheet where we have entered the names of the variables in the columns. Therefore, the numbers corresponding to countries run from 2 through 190. We will use these numbers as our label.

We will examine the entries in Table B in sets of three. Three digit numbers between 2 and 190 will correspond to selected countries. We will ignore three digit numbers equal to 000, 001, or greater than 190. Let’s start our selection at line 106 in Table B. The entries on this line are

68417 35013 15529 72765 85089 57067 50211 47487

If we arrange these into sets of three, we have

684 173 501 315 529 727 658 508 057 067 502 114 748 7

The selected labels from this set of random digits are 173, 057, and 067. Checking the spreadsheet, we see that these numbers correspond to Turkey, France, and Greece.

Note that we do not use the last digit on line 106 to select the country with the label 7. We should combine this single digit with the first two digits from line 107 of Table B. This gives us the three-digit number 782, which is a number that we ignore. We complete our selection of the additional 22 countries that we need in our SRS using additional lines from Table B as needed.