Systematic Sampling

What is systematic sampling?

There are many ways to take a sample from a population. One popular way is to take a systematic sample.

This article looks at this sampling method, and the precision of resulting estimates.

Taking a sample

Surveys help researchers answer questions about a population. There are units — like people or businesses — that make up a population.

In a simple random sample, every unit has an equal and non-zero probability of selection. Common examples would be bingo machines or lotteries. The selection machine gives each ball the same chance of appearing.

Systematic sampling assigns every unit a unique number. A systematic sample starts at a random point, then picks units at regular intervals.

Suppose there were 1,000 tents at a festival. The researcher wants to survey 100 tents. They pick a number between one and 10: such as seven. The researcher then chooses every tenth tent: 7th, 17th, 27th, 37th tents, and so on. The sample is then of 100 tents.

In the example, the researcher picks every third person in the systematic sample. (Image: Scribber)

There are several advantages to systematic sampling:

• Easier to conduct: Systematic samples are simpler to construct than simple random samples.
• Eliminating clusters: By chance, simple…