The determination of characteristics common to a group of people is:

The determination of characteristics common to a group of people is referred to as audience analysis. This process involves gathering information about the demographic, sociocultural, and psychological characteristics of individuals within a specific audience. By understanding these characteristics, instructors can tailor their content, teaching methods, and overall communication strategies to better engage and educate their audience. This customization is crucial for ensuring that the training is relevant, effective, and resonant with the learners' backgrounds and experiences.

Effective communication, while important, is more concerned with the clarity and delivery of the message rather than the analysis of the audience's characteristics. Blended learning refers to the combination of traditional face-to-face instruction with online learning, which is a method of delivery rather than an analytical process. The method of instruction pertains to the specific strategies or techniques used in teaching, but it does not focus on understanding the audience itself. Thus, audience analysis is the most relevant term for determining common characteristics among a group of people.