Data produced by an experimental or quasi-experimental design. In clinical research any data produced as a result of clinical trial. Experimental data may be qualitative or quantitative, each being appropriate for different investigations.
Generally speaking, qualitative data is considered descriptive or observational and, therefore, is relatively subjective in nature. Whereas quantitative data is gathered in a manner that is normally experimentally repeatable, qualitative information is usually more closely related to phenomenal meanings and is, therefore, subject to interpretation by individual observers.
In science, valuable experimental data is that which can be reproduced by a variety of different investigators and lends itself to mathematical analysis.