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Level of measurement or scale of measure is a classification that describes the nature of information within the values assigned to variables. [1] Psychologist Stanley Smith Stevens developed the best-known classification with four levels, or scales, of measurement: nominal, ordinal, interval, and ratio.
In music, an interval ratio is a ratio of the frequencies of the pitches in a musical interval. For example, a just perfect fifth (for example C to G) is 3:2 ( Play ⓘ ), 1.5, and may be approximated by an equal tempered perfect fifth ( Play ⓘ ) which is 2 7/12 (about 1.498).
The size of an interval between two notes may be measured by the ratio of their frequencies.When a musical instrument is tuned using a just intonation tuning system, the size of the main intervals can be expressed by small-integer ratios, such as 1:1 (), 2:1 (), 5:3 (major sixth), 3:2 (perfect fifth), 4:3 (perfect fourth), 5:4 (major third), 6:5 (minor third).
jiffy (physics) 3 × 10 −24 s: The amount of time light takes to travel one fermi (about the size of a nucleon) in a vacuum. zeptosecond: 10 −21 s: One sextillionth of a second. Time measurement scale of the NIST and JILA strontium atomic clock. Smallest fragment of time currently measurable is 247 zeptoseconds. [3] attosecond: 10 −18 s
Euclid defines a ratio as between two quantities of the same type, so by this definition the ratios of two lengths or of two areas are defined, but not the ratio of a length and an area. Definition 4 makes this more rigorous. It states that a ratio of two quantities exists, when there is a multiple of each that exceeds the other.
By definition, every interval in a given limit can also be part of a limit of higher order. For instance, a 3-limit unit can also be part of a 5-limit tuning and so on. By sorting the limit columns in the table below, all intervals of a given limit can be brought together (sort backwards by clicking the button twice).
A cent is a unit of measure for the ratio between two frequencies. An equally tempered semitone (the interval between two adjacent piano keys) spans 100 cents by definition. An octave —two notes that have a frequency ratio of 2:1—spans twelve semitones and therefore 1200 cents.
Interval (mathematics), a range of numbers Partially ordered set#Intervals, its generalization from numbers to arbitrary partially ordered sets; A statistical level of measurement; Interval estimate; Interval (graph theory) Space-time interval, the distance between two points in 4-space