Systematic Random Sampling – This technique is good for process sampling whereby you would randomly select your items using a fixed periodicity of time.

PPS Systematic 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 ...

The stratified random sample is always at least as accurate on the average as the random sample and its relative efficiency is a monotone increasing function of the size of the sample. No general ...

Stratified Sampling with Control Sorting The next sample design for the customer satisfaction survey uses stratification by State. The sampling frame is also sorted by Type and Usage before sample ...

In systematic random sampling, both the starting point and the sampling interval are determined by the required sample size. Stratified random sampling: Potential respondents are organized into strata ...

They concluded that systematic or stratified random sampling patterns are more effective than simple random sampling for bulk powder testing.

Random sampling would give an estimate of the total number but not show where they are in relation to the lake. In this case systematic sampling would be used instead. This is not random.

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.