Which of the following is an example of a quantitative research method?

Surveys with closed-ended questions are an example of a quantitative research method because they collect numerical data that can be statistically analyzed. This method involves asking participants a series of predetermined questions that require specific answers, often in the form of yes/no or multiple-choice responses. By converting qualitative opinions into quantifiable data, researchers can identify patterns, averages, and trends among different responses.

The other methods listed tend to focus on qualitative data collection, which is more exploratory in nature. Participant observation involves the researcher immersing themselves in a social setting to collect descriptive data, while focus group discussions facilitate in-depth conversations that yield rich, qualitative insights into people's attitudes and opinions. Case studies provide detailed examinations of a particular subject or scenario, focusing on contextual information rather than quantifiable statistics.

In contrast, surveys with closed-ended questions allow for straightforward comparison and analysis of numerical data, making them a quintessential example of quantitative research.