Deviation

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deviation

[‚dēv·ē′ā·shən]
(engineering)
The difference between the actual value of a controlled variable and the desired value corresponding to the set point.
(evolution)
Evolutionary differentiation involving interpolation of new stages in the ancestral pattern of morphogenesis.
(optics)
The angle between the incident ray on an object or optical system and the emergent ray, following reflection, refraction, or diffraction. Also known as angle of deviation.
(petroleum engineering)
During a drilling operation, the inclination of the borehole from the vertical.
(statistics)
The difference between any given number in a set and the mean average of those numbers.

Deviation

 

in artillery, an accidental phenomenon not allowed for in the laws of dispersion, by which shells (bullets) veer away from the mean trajectory expected under the given firing conditions. Causes of deviation may be the mechanical disruption of the movement of the shell in the bore (for example, separation of the shell from the rifling grooves) or in the air (for example, a defect in the stabilizer fins or other parts), as well as a chance sharp change in weather conditions during the flight of the shell.


Deviation

 

in biology, a variety of phylembryogenesis in which a change in the development of an organ arises in the middle stages of its formation and results in a change in the structure of the organ in the adult organism, compared with the same organ in its ancestors. For example, in the middle stages of development the epidermal part of the scale buds of reptiles undergoes keratinization, not ossification (as in sharks). The term “deviation” was introduced by the German scientist F. Müller (1864).


Deviation

 

the most common measure of dispersion, that is, deviation from the mean, in mathematical statistics and theory of probability. In the statistical sense, deviation

is the arithmetic mean of the squares of the deviations of the values Xi from their arithmetic mean

In the theory of probability the deviation (variance) of a random variable X is called the expected value E(X - mx)2 of the square of the deviation of X from its expected value mx =E(X). The deviation of a random variable X is denoted by D(X) or by σ2). The square root of the deviation (that is, if the deviation is σ2) is called standard deviation.

For a random variable X with continuous probability distribution, characterized by probability density p(x), deviation is calculated by the formula

where

The following theorem has great significance in the theory of probability: the deviation of the sum of independent terms is equal to the sum of their deviations. No less important is Chebyshev’s inequality, which allows us to evaluate the probability of large deviations of the random variable X from its expected value.

REFERENCE

Gnedenko, B. V. Kurs teorii veroiatnostei, 5th ed. Moscow, 1969.

deviation

deviation
deviation
i. The angular difference between a magnetic and a compass heading. It is a compass error caused by the compass magnet attempting to align with the aircraft's local magnetic field. The deviation error changes with the aircraft heading and the latitude. It is measured in degrees east (+) or west (−), depending on whether the north-seeking end of the compass needle lies to the east or west of magnetic north.
ii. The angle between the wind and the pressure gradient.
iii. In frequency modulation, the amount the carrier increases or decreases when modulated.
vi A departure from a current clearance, such as an off-course maneuver, to avoid bad weather or turbulence.
v A variation from set rules and regulations. Where specifically authorized in the regulation and requested by the pilot, ATC (air traffic control) may permit pilots to deviate from certain regulations.
vi. In flight, a sudden excursion from the normal flight path.
vii. The distance by which a weapon misses its target.
References in classic literature ?
In such a case, a plain and open avowal of his difficulties would have been more to his honour I think, as well as more consistent with his general character;--but I will not raise objections against any one's conduct on so illiberal a foundation, as a difference in judgment from myself, or a deviation from what I may think right and consistent.
He will conquer who has learnt the artifice of deviation.
There is that time, many years ago, when we did not act quite as honorably, quite as uprightly, as we perhaps should have done--that unfortunate deviation from the path of strict probity we once committed, and in which, more unfortunate still, we were found out--that act of folly, of meanness, of wrong.
Pfuel and his adherents demanded a retirement into the depths of the country in accordance with precise laws defined by a pseudo-theory of war, and they saw only barbarism, ignorance, or evil intention in every deviation from that theory.
Again the canyon veered sharply to the left, but to the right another branch ran on at a lesser deviation from the general direction, so that appeared more like the main canyon than the lefthand branch.
The sun rose in the undoubted east and set in the undoubted west, corrected and proved, of course, by declination, deviation, and variation; and the nightly march of the stars and constellations proceeded across the sky.
But, inasmuch as it is equally necessary to take into account the deviation which the rotary motion of the earth will impart to the shot, and as the shot cannot reach the moon until after a deviation equal to 16 radii of the earth, which, calculated upon the moon's orbit, are equal to about eleven degrees, it becomes necessary to add these eleven degrees to those which express the retardation of the moon just mentioned: that is to say, in round numbers, about sixty-four degrees.
If it did not land there, there must have been some deviation.
It will not be wondered at that a creature who had so strict a regard to decency in her own person, should be shocked at the least deviation from it in another.
This child's presence called up both in Vronsky and in Anna a feeling akin to the feeling of a sailor who sees by the compass that the direction in which he is swiftly moving is far from the right one, but that to arrest his motion is not in his power, that every instant is carrying him further and further away, and that to admit to himself his deviation from the right direction is the same as admitting his certain ruin.
At every turn and angle, even where a deviation from the direct course might have been least expected, and could not possibly be seen until he was close upon it, he guided the bridle with an unerring hand, and kept the middle of the road.
The story was repeated; it was, in effect, exactly the same as before, without any deviation or omission.