Probability sampling allows researchers to choose sections of the population they want represented in their sample. Non-probability sampling eliminates choosing desired sample constituents from a population. According to Family Health International, the three most common sampling methods for qualitative research are purposive,quota and snowball sampling, which are non-probability sampling. Purposive sampling allows the researcher to choose people or objects due to a specific purpose that enhances the study. Quota sampling includes choosing people or objects that are convenient yet random, such as stopping people in a mall to interview. Snowball sampling involves the researcher asking current subjects on ideas for other subjects with experiences similar to theirs to include in the study.
Probability and non-probability sampling ensures samples resemble a clear picture of the population. Subjects recruited randomly avoid sampling bias. Bias is any influence that can taint data. Purposive, quota and snowball sampling were created to minimize bias.
A common misconception is that qualitative studies require different subject recruiting techniques than quantitative research. Qualitative and quantitative research share some of the same subject recruiting procedures. The population or objects of the research assist researchers in determining which method of sampling is most appropriate.