Serious polling requires careful data collection and careful adjustment. It doesn't mean much to say your poll is a "probability sample" when your nonresponse rate is 90 percent.

In simple random sampling, each unit has an equal probability of selection, and sampling is without replacement. Without-replacement sampling means that a unit cannot be selected more than once.

One form of non-probability sampling is convenience sampling, meaning sampling based on accessibility and opportunity. For instance, we can draw our participants from patients at various hospitals.

A statistically designed random sampling scheme, based on as few as 100 people, would give a very high probability of detecting if there are any COVID-19 cases and highlight at-risk hotspots.

Ashley L. Buchanan, Michael G. Hudgens, Stephen R. Cole, Katie R. Mollan, Paul E. Sax, Eric S. Daar, Adaora A. Adimora, Joseph J. Eron, Michael J. Mugavero, Generalizing evidence from randomized ...

We assume that the natural first-phase sample is collected with probability of selection proportional to size for each unit. The objective is then to use the ranked set sampling procedure to obtain a ...

Systematic sampling is low risk, controllable and easy, but this statistical sampling method could lead to sampling errors and data manipulation.

In a simple random sample, each individual in the population has an equal probability of being chosen. Additionally, each sample of size n has an equal probability of being the chosen sample. This ...