Geographical mile longitude at the equator is thus exactly 60 geographical miles. It was closely related to the nautical mile, which was originally determined as 1 minute of arc along a great circle of the Earth, but is nowadays defined as exactly 1852 metres. The US National Institute of Standards and Technology (NIST) notes that: "The international nautical mile of 1 852 meters (6 076.115 49...feet) was adopted effective July 1, 1954, for use in the United States. The value formerly used in the United States was 6 080.20 feet = 1 nautical (geographical or sea) mile." (6080.2 feet is 1853.24496 meters.)
Theory of conjoint measurement to some kind of unit difference. Each level of "P" is a difference between the levels of "A" and "X". However, it is not clear from the literature as to how a unit could be defined within an additive conjoint context. proposed a scaling method for conjoint structures but he also did not discuss the unit. The theory of conjoint measurement, however, is not restricted to the quantification of differences. If each level of "P" is a product of a level of "A" and a level of "X", then "P" is another different quantity whose measurement is expressed as a