eitodennäköisyysotanta

Eitodennäköisyysotanta, often translated as non-probability sampling, refers to sampling methods where the selection of elements is not random. This means that each member of the population does not have an equal or known chance of being included in the sample. The choice of participants is based on the researcher's judgment, convenience, or specific criteria. This contrasts with probability sampling, where randomness is the core principle.

Several types of non-probability sampling exist. Convenience sampling involves selecting individuals who are readily available and accessible. Quota sampling aims to create a sample that reflects certain characteristics of the population, but the selection within those quotas is non-random. Purposive sampling, also known as judgmental sampling, involves the researcher hand-picking individuals based on their expertise or specific knowledge relevant to the study. Snowball sampling is used when the target population is difficult to identify or access, and existing participants are asked to refer other potential participants.

Non-probability sampling is often employed for exploratory research, pilot studies, or when probability sampling is impractical due to time, cost, or accessibility constraints. It can be quicker and more cost-effective. However, a significant limitation is that the results may not be generalizable to the broader population. The lack of random selection introduces potential biases, making it difficult to estimate sampling error and infer findings to the entire population with statistical confidence. Researchers using non-probability sampling must carefully consider these limitations and acknowledge them in their findings.