When the concepts were first introduced, the definition of the three R's was loosely formulated to include the range of techniques which might reduce the number of animals used in research or diminish their suffering in the course of the existing research. The scope of the modern definitions of these words has been modified to reflect the increased awareness and willingness of alternatives opponents to consider these options as feasible and beneficial efforts. Refinement of experimental procedures is one of the three R's because of the potential for reducing the amount of pain or distress that refined procedures might enable. Refinement, as the name suggests, entails the utilization of well-analyzed techniques that have been made as efficient and harmless as possible. However, refining procedures is not only good for the animals involved, since refined procedures may prove to be more reliable ones as well, thus refinement would improve the usability of the acquired data.
Reduction simply refers to minimizing the absolute number of animals subjected to experimentation.
This idea has met with some opposition by people who earn their living doing animal research because a superficial analysis of this specific aim may lead to the assumption that reduced animal experimentation means reduced experimentation as a whole, reduced jobs, etc. This fact is born out in recent data that show that the number of animals used worldwide is steadily decreasing while the amount of research being produced remains stable. The only research made obsolete by reduction of animal use is unnecessary replication studies. Replication of findings is undeniably an essential component of the discovery process, however without the proper communication of the replicated findings, many other replications are likely to be performed unnecessarily. Reduction would also necessitate proper study planning in order to minimize the amount of animals used in unnecessary manipulations, such as probing for effective doses in a particular drug-efficacy paradigm when the necessary data may already exist in the literature.