Systematic sampling
Systematic sampling is where we select every
For example, asking every 10th person who walks along a street to be in the sample.
Systematic sampling is where we select every
k th member of the population to be in our sample - at regular intervals.
Advantages of systematic sampling
- It’s easy to understand.
- Easier to implement than other sampling methods, because we don’t need to
randomly select members of the population or even know anything about it - we# just need to select every
k th member. - It’s unbiased, because every member of the population has an equal chance of being selected for the sample (as long as we start at a random point in the population).
Disadvantages of systematic sampling
- It may not give us a representative sample, because we might by chance select a sample that is not representative of the population (e.g. we might select a sample that is all from one area, or all from one age group, etc.).
- It can be difficult to implement, if we can’t feasibly survey every
k th member of the population (e.g. they live in a large area). - It might be biased if there is a pattern in the population that coincides with the sampling interval (e.g. if we select every 10th person, and every 10th person happens to be from a certain area or age group, then our sample will be biased).