Final answer:
Qualitative research involves subjective evidence, while quantitative research involves hard, specific data. The choice of research method depends on the study's objectives and the type of data needed.
Step-by-step explanation:
Qualitative research involves subjective evidence that is difficult to control and difficult to replicate. For example, if a researcher observes a classroom, business, or hospital setting, their observations are limited to what they observe at that particular location on that particular day at that particular time.
Quantitative research involves hard, specific data that can be replicated in a controlled environment. Authors of case studies use quantitative research by looking at data drawn from a group and using it as a basis for their findings. In other words, the data, not the researchers' observations, form the primary evidence.
The many methods available to researchers, such as interviews, surveys, ethnographic field studies, content analysis, and comparative historical secondary data analysis, have advantages and disadvantages. The strength of a study can depend on the choice and implementation of the appropriate method of gathering data.