Descriptive research explores phenomena in their natural environment without using the scientific method. Sometimes it is ethically impossible to use the scientific method to determine causal relationships between variables. In those cases, the descriptive method in research yields systematic information about something without impinging on the rights of research subjects.
Researchers want to know general information about human beings, such as what factors lead to excessive drinking among college students and what the results of this practice might be. An experimental research design would divide random college students in two groups, asking one group to drink a lot of alcohol and the other to abstain. This would be a completely unethical study because it would put the research subjects in danger. Instead of putting subjects in danger, researchers use various forms of descriptive research, which can include having the students fill out surveys, observing students' behavior in various settings and interviewing students. In this way, researchers can study students who self-select drinking behaviors. While descriptive research can yield rich descriptions of factors that may be associated with drinking behavior, it cannot determine causal factors between variables the way experimental research can. This is because descriptive research does not isolate variables the way experiments do.