specimen role control specimen role A control specimen role of a biotic or abiotic sample or individual describes a specimen by its purpose, and therefore treatment, within a planned experimental process that tests hypotheses by isolating variables as dictated by the scientific method in order to make a conclusion about the effect of such variables. The quality of control inhering in the sample role exists as a result of the historical treatment of the sample. In a controlled experiment, two or more virtually identical experiments are conducted, but the factor being tested is varied in only one of them. This serves to isolate any causal phenomena. A control may have been subject to treatments during the experiment that might alter its state or behaviour and is therefore distinguishable from the sample as initial input into the experiment. However such treatments should in all cases but that of the variable under scrutiny, be the same as the experimental sample. http://ncicb.nci.nih.gov/xml/owl/EVS/Thesaurus.owl#C64355