Suppose you selected a sample from Table 2.2 by starting with the number in row 1, column 2. You then proceed across the row, skipping the next five numbers and take the sixth number. You continue in this way, skipping five numbers and taking the sixth, going to the leftmost element in the next row when all the elements in a row are exhausted, until you have exhausted the table.

a. What is such a sample selection scheme called?

b. Could any possible sources of bias arise from using this scheme?