Systematic sampling is a probability sampling method where samples from a larger population are selected according to a random starting point but with a fixed, periodic interval. This sampling ...

If you specify the option METHOD=PPS_SYS, PROC SURVEYSELECT selects units by systematic random sampling with probability proportional to size. Systematic sampling selects units at a fixed interval ...

PROC SURVEYSELECT provides the following methods that select units with probability proportional to size (PPS): PPS sampling without replacement, PPS sampling with replacement, PPS systematic sampling ...

With systematic sampling you can then select the points ... of one species or the number of different species. Whatever the method, respect the species you're studying by leaving everything ...