“Empirical evidence includes measurements or data collected through direct observation or experimentation,” said Jaime Tanner, a professor of biology at Marlboro College in Vermont. There are two research methods used to gather empirical measurements and data: qualitative and quantitative.
Qualitative research, often used in the social sciences, examines the reasons behind human behavior, according to Oklahoma State University. It involves data that can be found using the human senses. This type of research is often done in the beginning of an experiment.
Quantitative research involves methods that are used to collect numerical data and analyze it using statistical methods, according to the IT University of Copenhagen. Quantitative numerical data can be any data that uses measurements, including mass, size or volume, according to Midwestern State University, in Wichita Falls, Texas. This type of research is often used at the end of an experiment to refine and test the previous research.