Final answer:
The method common in market research and advertising for studying multiple units of analysis and obtaining detailed responses is a focus group, which involves moderated group discussions.
Step-by-step explanation:
Common Method in Market Research and Advertising
The method that is common in market research and advertising, allowing researchers to study multiple units of analysis at one time and often get detailed responses from each, is focus group. A focus group involves a moderated discussion with a small group of people to gather diverse opinions, beliefs, and attitudes about a particular product, service, concept, or advertisement. This method is valuable for obtaining rich qualitative data and gauging consumer response.
In the broader field of social investigation, sociologists and researchers select from a range of methods such as surveys, ethnographic research, interviews, historical data analysis, and content analysis, each with its set of assets and limitations. The choice of the appropriate method is guided by the research question and objectives, and while a method like content analysis seeks to interpret and analyze communication artifacts, a case study provides an in-depth analysis of a single event, situation, or individual.