(biology, sociology) The ratio of males to females in any given population.

(philosophy) “Right reason”, which regards virtue as desirable in itself.

In radioactivity, the portion of all decays that take a given pathway. For example, californium-252 decays by alpha decay ~97% of the time, and by spontaneous fission ~3% of the time; so the branching ratio is about 0.97 in favor of alpha decay, and about 0.03 in favor spontaneous fission.

(medicine) The ratio (MRD + MLD) / ID, where MRD is the greatest perpendicular diameter from midline to right heart border; MLD is the greatest perpendicular diameter from midline to left heart border; and ID is the internal diameter of the chest at the level of the right hemidiaphragm.

Alternative form of S/F ratio

Alternative form of P/F ratio

(mathematics) The ratio of each term of a geometric progression to the term preceding it.

(film, television) The ratio between the total duration of footage created for possible use in a project and the duration used in the final cut.

(law) legal philosophy under which penal redress to crime should only be used as a measure of last resort

(finance) A ratio that measures the excess return (or risk premium) per unit of deviation in an investment asset or a trading strategy, used to examine the performance of an investment by adjusting for its risk.