Ryväsnäytteistys

Ryväsnäytteistys, also known as cluster sampling, is a statistical sampling method. It is a probability sampling technique where researchers divide a population into a group of subgroups, known as clusters. These clusters are typically pre-existing, natural groupings within the population, such as geographical areas, schools, or households.

The process involves selecting a random sample of these clusters. Once the clusters are chosen, all individuals within the selected clusters are included in the sample. Alternatively, a second stage of sampling might occur within the chosen clusters, where a random sample of individuals is then selected from each cluster. This is known as two-stage cluster sampling.

Ryväsnäytteistys is often used when it is impractical or too costly to obtain a complete list of all individuals in a population, or when the population is geographically dispersed. It can be more cost-effective and efficient than simple random sampling or stratified sampling in such situations. However, it can also lead to higher sampling error if the clusters are not representative of the entire population, meaning that individuals within a cluster are more similar to each other than they are to individuals in other clusters. Careful consideration of cluster selection and size is crucial for ensuring the validity of the results obtained through ryväsnäytteistys.