Identify which type of sampling is used: random, systematic, convenience, stratified, or cluster. Upper A magazine asks its readers to call in their opinion regarding the quality of the articles.

Convenience sampling

Step-by-step explanation:

Convenience sampling is a type of non-probability sampling method that is used base on the ease of access to subjects or people. The only criteria is whether the participants agree to participate. It is the most commonly used sampling technique because it is readily available, easy to access, prompt, uncomplicated, and economical. Although it is not often recommended for research because of sampling error possibility and lack of representation of population. Examples of convenience sampling are sharing flyers of upcoming events or promotion in a shopping mall, asking people to answer questions in a store, online and offline survey and collecting market research data from a conveniently available pool of respondents.

Considering, Upper A magazine asks its readers to call in their opinion regarding the quality of the articles is a convenient way of collecting market research data from available readers who may agree to participate. Therefore, the sampling is a convenience sampling.