In quantitative research, the research methods focus on quantifying gathering and analysis of data. This type of study follows the deductive method of investigation, which favors testing theory and testing its validity. This methodology is often influenced by the positivist and empiricist philosophies. It uses statistical and mathematical methods to examine and compare different variables and results. It is a powerful tool for the testing of hypotheses and theories. It is used in many fields of research.

Qualitative research focuses on how people think and why they act, and quantitative research focuses on how they behave and what actions they take. Both methods are useful for understanding why people behave the way they do. Whether qualitative and quantitative methods are complementary is up to the researcher. Quantitative research can be a valuable complement to qualitative research. Using both to test hypotheses is called mixed methods research. But quantitative research cannot completely replace qualitative methods, because it is not very good at discovering the why of human behavior.

In the field of social science, correlational research is an important quantitative tool for studying relationships. This method is based on mathematical analysis, which requires a large number of subjects to make a statistically significant conclusion.