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 ...

With systematic sampling you can then select the points to monitor but this can introduce bias. Random sampling eliminates bias by generating the points randomly. Now you need sampling tools.

Key fact Most sampling is random, 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 ...

and that larger samples are more likely to be closer to the true population value (assuming there is no systematic bias). A thought experiment about sampling distributions: Imagine you take a random ...