Final answer:
Qualitative research uses interviews and analysis of content, observation research relies on direct observation, surveys collect data through questionnaires, and experiments test cause-and-effect relationships in controlled environments.
Step-by-step explanation:
Each research design in business has its own strengths and limitations. Qualitative research focuses on understanding human behavior through in-depth interviews, focus groups, and content analysis. Observation research involves observing subjects in natural settings, while surveys collect data through a series of questions. Experiments are conducted in controlled environments to test cause-and-effect relationships. It's important to choose the appropriate research design based on the topic and research question.