Eitodennäköisyysotantaa

Eitodennäköisyysotantaa, known in English as non-probability sampling, is a sampling method where the selection of participants is not based on random chance. Instead, the researcher uses their judgment and discretion to select individuals who they believe will best serve the purposes of the study. This contrasts with probability sampling, where every member of the population has a known, non-zero chance of being selected.

There are several types of non-probability sampling. Convenience sampling involves selecting participants who are readily available and easy to access. Purposive sampling, also known as judgmental sampling, relies on the researcher's expertise to choose participants who are considered to be representative of the population or who possess specific characteristics relevant to the study. Quota sampling aims to create a sample that mirrors the proportions of certain characteristics in the population, but the selection within those quotas is not random. Snowball sampling is used when the target population is difficult to identify or access; existing participants are asked to refer other potential participants.

Non-probability sampling is often employed in qualitative research due to its flexibility and cost-effectiveness. It can be useful for exploratory studies or when a comprehensive list of the target population is unavailable. However, a significant limitation is that it does not allow for generalization of findings to the broader population with statistical confidence, as the sample may be biased. The lack of random selection means that sampling error cannot be calculated, and the validity of the results can be questioned. Researchers using non-probability sampling must be transparent about their methodology and acknowledge the inherent limitations when interpreting their findings.