A sample of respondents which is available to researchers because of their access to the respondents is identified as

Convenience sampling draws respondents simply because they are easily accessible to the researcher.

Random sampling gives every population unit a known equal chance of selection.

Quota sampling fills preset category quotas from the population.

Snowball sampling relies on early respondents recruiting others through their networks.

Being a non-probability method, it carries a high risk of selection bias.

Its cheapness and speed make it common in exploratory studies.