Investigation is one of the most commonly used methods in scientific research. It is a purposeful, planned and systematic collection of the actual situation or history of the research object. Questionnaire survey is the most commonly used survey method, and it is a research method to collect data in the form of written questions, that is, investigators prepare forms for survey items, distribute or mail them to relevant personnel, ask for instructions to fill in answers, and then recycle, sort out, count and study them.

2. Observation method.

Observation method refers to a method in which researchers use their own senses and auxiliary tools to directly observe the research object according to a certain research purpose, research outline or observation table, so as to obtain information. Scientific observation is purposeful, planned, systematic and repeatable. In scientific experiments and investigations, observation has the following functions: ① Expanding people's perceptual knowledge. 2 inspire people's thinking. (3) lead to new discoveries.

3. Experimental methods.

Experimental method is a scientific research method to discover and confirm the causal relationship between things by changing the main branch and controlling the research object.