Epätodennäköisyysotantaa

Epätodennäköisyysotantaa, or non-probability sampling, is a sampling technique where the selection of participants is not based on random chance. Instead, the researcher relies on their own judgment or convenience to choose individuals for the sample. This approach differs from 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 accessible to the researcher. Quota sampling aims to create a sample that reflects the proportions of certain characteristics found in the population, but the selection within those quotas is non-random. Purposive sampling, also known as judgmental sampling, involves the researcher using their expertise to select participants who they believe will be most informative for the study. Snowball sampling is used when the target population is difficult to access; existing participants are asked to refer other potential participants.

The main advantage of non-probability sampling is its cost-effectiveness and speed, making it a practical choice for exploratory research or when resources are limited. However, a significant drawback is that it does not allow for generalization of findings to the broader population with statistical confidence. This is because the non-random selection process can introduce selection bias, meaning the sample may not be representative of the population. Therefore, results from non-probability samples should be interpreted with caution.