Experimental replication

Reproducibility is one of the main principles of the scientific method, and refers to the ability of a test or experiment to be accurately reproduced, or replicated. The term is very closely related to the concept of testability and, depending on the particular field, may require the test or experiment to be falsifiable.

The results of an experiment performed by a particular researcher or group of researchers are generally evaluated by other independent researchers by attempting to reproduce the original experiment; they repeat the same experiment themselves, based on the original experimental description, and see if their experiment gives similar results to those reported by the original group. The result values are said to be commensurate if they are obtained (in distinct experimental trials) according to the same reproducible experimental description and procedure.

Experiments which cannot be reliably reproduced are generally not considered to provide useful scientific evidence. Results which prove to be highly reproducible are typically given more credence by scientists than those which are less reproducible, although this is based on an intuitive application of the principle of induction, rather than on the strict application of the principles of falsifiability.

The basic idea can be seen in Aristotle's dictum that there is no scientific knowledge of the individual, where the word used for individual in Greek had the connotation of the idiosyncratic, or wholly isolated occurrence. Thus all knowledge, all science, necessarily involves the formation of general concepts and the invocation of their corresponding symbols in language (cf. Turner).

Reproducibility is also the variation in measurements taken by different persons or instruments on the same item and under the same conditions.

The case of cold fusion

 * See main article at Cold Fusion

In the late 1980's there was a rush to publish on the subject of cold fusion, a technology that offered promise of low-cost energy. In March 1989, University of Utah chemists Stanley Pons and Martin Fleischmann reported the production of excess heat that could only be explained by a nuclear process. The report was astounding given the simplicity of the equipment: it was essentially an electrolysis cell containing heavy water and a palladium cathode which rapidly absorbed the deuterium produced during electrolysis. The newsmedia reported on the experiments widely, and it was a front-page item on many newspapers around the world. Over the next several months others tried to replicate the experiment, but were unsuccessful. At the end of May the US Energy Research Advisory Board formed a special panel to investigate cold fusion. The scientists in the panel found the evidence to be unconvincing. Pons and Fleischmann later apparently claimed that there was a "secret" to the experiment, a statement that infuriated the majority of scientists to the point of dismissing the experiment out of hand. the science of cold fusion was severely damaged by the affair, although research continues quietly around the world.