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 ...

but systematic sampling can be used if there is a trend or pattern across the habitat, such as distance up a beach, or altitude on a hillside. If you are using the wrong kind of sampling method ...

The greater bilby (Macrotis lagotis) is one of Australia’s most iconic yet at-risk animals — and the last surviving bilby species. Once found across 70% of Australia, its range has contracted by more ...

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 ...