In science, parsimony is preference for the least complex explanation for an observation. This is generally regarded as good when judging hypotheses. Occam's razor also states the "principle of parsimony".
In systematics, maximum parsimony is a cladistic "optimality criterion" based on the principle of parsimony. Under maximum parsimony, the preferred phylogenetic tree is the tree that requires the smallest number of evolutionary changes.
In biogeography, parsimony is used to infer ancient migrations of species or populations by observing the geographic distribution and relationships of existing organisms. Given the phylogenetic tree, ancestral migrations are inferred to be those that require the minimum amount of total movement.
Parsimony is also a factor in statistics: in general, mathematical models with the smallest number of parameters are preferred as each parameter introduced into the model adds some uncertainty to it. Additionally, adding too many parameters leads to "connect-the-dots" curve-fitting which has little predictive power. In general terms, it may be said that applied statisticians (such as process control engineers) value parsimony quite highly.
Lee and others provide cases where a parsimonious approach does not guarantee to arrive at a correct conclusion, and if based on incorrect working hypotheses or interpretations of incomplete data may even strongly support a false conclusion:
When parsimony ceases to be a guideline and is instead elevated to an ex cathedra pronouncement, parsimony analysis ceases to be science.
For another example using a more familiar subject, consider the attempts to determine the relationships of the cockatoos, namely such taxa as the Gang-gang Cockatoo, the Galah, and the popular pet, the cockatiel. It becomes obvious that parsimony is an extremely powerful tool if the researcher is able to interpret correctly the significance of the data to the case in question, and is able to relate and put it into context inter se. Failure to fulfil these conditions will, speaking figuratively, dull Occam's razor fairly quickly.
Areas of endemism of Mexican terrestrial mammals: a case study using species' ecological niche modeling, Parsimony Analysis of Endemicity and Goloboff fit/ Areas de endemismo de mamiferos terrestres de Mexico: un caso de estudio usando modelos de nicho ecologico, Analisis de Parsimonia de Endemismos y ajuste de Goloboff/ Areas de endemismo dos mamiferos terrestres do Mexico: um estudo de caso usando modelamento de nicho ecologico ...
Mar 01, 2007; SUMMARY Areas of endemism of Mexican terrestrial mammals using ecological niche modeling projected as species' potential...