| 释义 |
precision|prɪˈsɪʒən|
[a. F. précision (16th c. in Godef.) or ad. L. præcīsiō-nem a cutting off abruptly, n. of action f. præcīdĕre: see precise a.]
1. a. The fact, condition, or quality of being precise; exactness, definiteness; distinctness, accuracy.
arm of precision: a fire-arm fitted with mechanical aids, such as rifling, graded sights, etc., which make it more accurate of aim than weapons without these.
1740Cheyne Regimen Pref. 12 Precision is incompatible with Finitude. 1771H. Walpole Vertue's Anecd. Paint. IV. i. 26 He knew how to omit exactness, when the result of the whole demands a less precision in parts. 1824L. Murray Eng. Gram. (ed. 5) I. 438 Precision is the third requisite of perspicuity with respect to words and phrases. It signifies retrenching superfluities, and pruning the expression, so as to exhibit neither more nor less, than an exact copy of the person's idea who uses it. 1860Motley Netherl. (1868) I. ii. 36 A right-angled triangle of almost mathematical precision. 1877Huxley Physiogr. Pref. 6 The precision of statement, which..distinguishes science from common information. 1906Lists Techn. Terms Army Schools i. Gunnery & Artillery 8 Precision..[definition] Exactness, accuracy.
†b. With a and pl. An instance of precision; a nicety; in pl. exact minutiæ. Obs. rare—1.
1691Locke Lower. Interest Wks. 1727 II. 92, I have left out the utmost Precisions of Fractions in these Computations.
c. Statistics. The reproducibility or reliability of a measurement or the like; used spec. to denote various measures or indices of this (see quots.). [The sense is due to W. Lexis, who used G. präcision (now präzision) (W. Lexis Zur Theorie der Massenerscheinungen in der menschlichen Gesellschaft (1877) ii. 25).]
1885M. Merriman Textbk. Method of Least Squares i. 1 The comparison of observations is necessary in order to determine the relative degrees of precision of different sets of measurements made under different circumstances. 1906Acta Univ. Lundensis Ny Följd I. v. 7, k is called the measure of precision. 1911G. U. Yule Introd. Theory Statistics xiii. 253 The reliability or precision of an observed proportion varies as the square root of the number of observations on which it is based. Ibid. xv. 304 The use of √2 × σ (the ‘modulus’) as a measure of dispersion, of 1/× √2·σ as a measure of precision, and of 2σ2 as ‘the fluctuation’. 1947O. L. Davies Statistical Methods in Res. & Production 250 The normal distribution..is given by some writers the mathematical formulation: he-h²x²/√π. The parameter h is then called the parameter of precision, but by comparison with the usual formula it is seen that this parameter is related to the standard deviation by the identity h = 1/σ√2. 1949F. Yates Sampling Methods for Censuses & Surveys viii. 247 The relative precision of two different methods of sampling based on the same type of sampling unit may be defined as the reciprocal of the ratio of the sampling variances of the estimates given by the two methods when the same number of units are taken. 1957Kendall & Buckland Dict. Statistical Terms 224 Precision is a quality associated with a class of measurements and refers to the way in which repeated observations conform to themselves; and in a somewhat narrower sense refers to the dispersion of the observations, or some measure of it, whether or not the mean value around which the dispersion is measured approximates to the ‘true’ value. In general the precision of an estimator varies with the square root of the number of observations upon which it is based. 1965R. Deutsch Estimation Theory x. 154 Precision is a measure of how close the outcome of a measurement, or a sequence of observations, clusters about some estimated value of a specified parameter. 1965D. V. Lindley Introd. Probability & Statistics II. v. 8 We shall call the inverse of the variance, the precision. The nomenclature is not standard but is useful. 1971Nature 12 Feb. 484/1 An estimate of the precision (analytical reproducibility) of each K{b1}Ar analysis is given as a {pm} value. 1974IEEE Trans. Instrumentation & Measurement XXIII. 278/1 The desired precision of intercomparison was set at {pm}0·01µV (one part in 108). 1974Nature 8 Nov. 137/1 Radioactive isotopic dates invariably include their precision, that is, the repeatability, yet most earth scientists still take these figures as measures of accuracy.
d. In numerical work, the fineness of specification, as represented by the number of digits given and distinguished from accuracy (the nearness to the true value).
1948Math. Tables & Other Aids to Computation III. 286 Numbers are stored to a precision of 35 binary digits. 1956G. A. Montgomerie Digital Calculating Machines vii. 12 Precision can be expressed in two ways: we may say that a number is correct to so many decimal places or to so many significant figures. 1962Gloss. Terms Automatic Date Processing (B.S.I.) 14 A result may have more precision than it has accuracy, e.g. the true value of π to eight decimal figures is 3·1415927; the expression π = 3·1415249 is precise to eight figures but accurate only to about five. 1970H. A. Rodgers Dict. Data Processing Terms 81/1 Strictly speaking there is a difference of precision between 1,000 and 1. × 103; in the first case the low-order zeros are known to have that value while in the second case all that is known is the explicit digit and the multiplier. 1972Physics Bull. Aug. 459/2 To precisions varying from 1 to 0·01 parts in a million, the value of (2e/h)J does not depend on whether the effects are observed in absorption or emission.
†2.
a. The cutting off of one thing from another; esp. the mental separation of a fact or idea; abstraction; in quot. 1640, a cutting short; in quot. 1683 = reservation 4. Obs. (App. used for prescission, as the n. corresponding to prescind v.)
1640G. Watts tr. Bacon's Adv. Learn. v. v. 255 We call Prenotion a Precision of endlesse investigation. 1681Glanvill Sadducismus i. App. §8 When, from this mental Precision of Cogitation from Extension, he defined a Spirit. Ibid., From the precision of our thoughts to infer the real precision or separation of the things themselves, is a very putid and puerile sophism. 1683A. D. Art Converse 95 You can neither tye them by Promise, nor by Oath; for if they Promise or Swear, 'tis with a mental Precision. 1710Berkeley Princ. Hum. Knowl. Introd. §9 As the mind frames to itself abstract ideas of qualities or modes, so does it, by the same precision, or mental separation, attain abstract ideas of the more compounded beings which include several coexistent qualites.
†b. transf. A precise definition. Obs. rare.
1690Locke Hum. Und. iii. x. §15 The taking Matter to be the Name of something really existing under that Precision,..has..produc'd..obscure..Discourses. 1757E. Griffith Lett. Henry & Frances (1767) II. 186 This definition I look upon to be more imperfect, and of a more dangerous tendency, than any of the three precisions he has so ingeniously proved the insufficiency of.
3. a. attrib. and Comb., usu. implying an intended or actual precision of performance, execution, or construction.
1875Encycl. Brit. III. 263/1 The theory of the common balance as we see it working in every grocer's shop, and..of the modern precision balance. 1910Westm. Gaz. 6 Jan. 4/2 Those wonderful American automatic precision tools that have played so conspicuous a part in almost every European factory. 1935Discovery Jan. 9/1 Continuous knife-edges and continuous knife-edge bearings such as are now used in all precision balances. Ibid. Dec. 368/2 The optical outfits..consist of precision-made parts, the mere use of which teaches precision in working. 1937Ibid. Apr. 112/1 These are real precision instruments,..with lens of aperture FI·9 such as the old plate cameras never knew. 1939War Illustr. 16 Dec. 440/3 The barrage..gives London and other cities and vital points reasonable security from swooping raiders and precision-bombing. 1944Foundry Feb. 116/1 Application of precision casting, utilizing either centrifugal or pressure methods, to the production of precision parts made from heat and corrosion resistant alloys is a recent development. 1950N.Y Times Mag. 27 Aug. 52/2 Strategic bombing as carried out by the American 8th and 15th Air Forces in Europe was ‘precision bombing’ directed, so far as operational accuracy permitted, against specific military targets. 1951People 3 June 7/7 (Advt.), Just switch on that precision-built Arvin and discover for yourself how pleasant dry shaving can be. 1953‘N. Blake’ Dreadful Hollow 77 Yes, quite a precision-tool job. 1957Technology Mar. 10/2 Other work includes..the repair of indicator gauges and other precision instruments. 1963New Yorker 23 Nov. 23 (Advt.), What's low in upkeep, high in mileage,..precision-engineered with 42 hidden changes to date but looks the same every year? 1966‘H. MacDiarmid’ Company I've Kept viii. 187, I qualified as a precision fitter and obtained a job with a big general engineering firm. 1969‘D. Rutherford’ Gilt-Edged Cockpit x. 172 We still think there's a market for individuality and a precision-built car. 1975Bram & Downs Manuf. Technol. i. 7 Gauge blocks are used as standards of measurement or reference in most precision-engineering works. 1976J. van de Wetering Corpse on Dike (1977) ii. 33 Mary kept her pistols in the drawer... ‘Careful... They are precision instruments, both of them.’
b. Special Comb.: precision approach radar, a ground-based radar system used to follow accurately the approach of an aircraft and to enable landing to be supervised from the ground.
1950Electronics Feb. 71/1 (heading) Airport surveillance and precision approach radar (GCA). 1956Electronic Engin. XXVIII. 15/2 In practice, all airport radar requirements except precision approach radar..can be met. 1965Nayler & Ower Aviation xvii. 250/2 Ground Controlled Approach.., also known as Precision Approach Radar, gives the position of an approaching aircraft in elevation, azimuth, and range relative to the touch-down point on the runway.
Hence preˈcisional a., of or pertaining to precision; preˈcisioner, = precisionist n.; preˈcisionism, practice of precision (see also precisianism); preˈcisionize v. trans., to give precision to, state with precision or accuracy.
1874Bushnell Forgiveness & Law ii. 127 The old *precisional drill, that came so hard upon the soldier at first.
1902Times 15 July 10/2 It is not an air to be breathed freely by pedants, or prudes, or *precisioners.
1868H. Kingsley Mlle. Mathilde II. vi. 94 She had disliked André Desilles and his *precisionism all her life.
1847Sir G. C. Lewis Lett. (1870) 153 What a pity the same man does not, in the same manner, *precisionize other..questions of political morals. 1895Dublin Rev. Oct. 303 To precisionise the successive whens and wheres. |