Empirical research is any activity that uses direct or indirect observation as its test of reality. If atheoretical, it is a form of inductive reasoning. It may also be conducted according to hypothetico-deductive procedures, such as those developed from the work of R. A. Fisher.
The empirical researcher attempts to describe accurately the interaction between his instrument (which may be as simple as the human eye) and the entity being observed. The researcher is expected to calibrate his instrument by applying it to known standard objects and documenting the results before applying it to unknown objects.