Step 4. For each of the first k + 1 ranked samples, select the unit with rank
k + 1 for actual measurement.
Step 5. For each of the last k + 1 ranked samples, i.e., the
n − kth to the nth
ranked sample, select the unit with rank n − k for actual measurement.
Step 6. For j = k + 2 n − k − 1, the unit with rank j in the jth ranked
sample is selected for actual measurement.
Step 7. The cycle may be repeated r times to obtain the desired sample size n∗r.