Qualitative observation in science is when a researcher subjectively gathers information that focuses more on the differences in quality than the differences in quantity, which usually involves fewer participants. Qualitative observation is more interested in bringing out and knowing all of the intimate details about each participant and is conducted on a more personal level so that the researcher can get the participants to confide in the researcher.
When participants feel comfortable with the researcher and confide in him or her, the researcher is able to get the information that he or she needs to make concrete observations. Most qualitative observational studies take place in a natural setting such as a public place and ask that participants answer questions in their own words. Qualitative observations and studies are usually done by social scientists, psychologists and sociologists with the goal of better understanding human and animal behavior.
Quantitative observation, on the other hand, is an objective gathering of information. It focuses on things such as statistics, numeric analysis and measurements. Quantitative observation typically measures things, such as shapes, sizes, color, volume and numbers looking for the differences between the test subjects. It is the most commonly used observational method except for the social sciences where qualitative observation is the most commonly used observation method.