| 单词 | standard deviation |
| 释义 | > as lemmasstandard deviation d. Statistics. The amount by which one of a set of measurements, numerical observations, etc. differs from the arithmetical mean of the whole set; standard deviation, a common measure of the scatter or dispersion of a set of measurements, equal to the square root of the mean of the squares of the deviations. ΚΠ 1858 W. Greener Gunnery in 1858 375 The mean deviation on the target from the centre of the group of 10 hits being only ·85 of a foot at 500 yards' range. 1875 F. Galton in London, Edinb. & Dublin Philos. Mag. 4th Ser. 49 35 Medium values will occur very much more frequently than extreme ones, the rarity of the latter rapidly increasing as the deviation slowly increases. 1895 K. Pearson in Philos. Trans. 1894 (Royal Soc.) A. 185 80 Then σ will be termed its standard-deviation (error of mean square). 1895 K. Pearson in Philos. Trans. 1894 (Royal Soc.) A. 185 104 We have no less than three measurements deviating by more than four times the standard-deviation from the mean. 1925 R. A. Fisher Statist. Methods iii. 46 A deviation exceeding the standard deviation occurs about once in three trials. Twice the standard deviation is exceeded only about once in 22 trials. 1946 F. J. Schonell Backwardness in Basic Subj. (ed. 3) v. 80 This is at a point 1·6 standard deviations from the mean of the normal population group. 1968 J. H. Burn Lect. Notes Pharmacol. (ed. 9) 135 The standard deviation usually makes the scatter look greater than the average deviation makes it look. Thus for the cocaine figures, using the standard deviation we have 57·5 ± 23·1 mg. per kg., instead of 57·5 ± 16·2 mg. per kg. 1970 Nature 12 Dec. 1081/1 In VLF data handling we usually assume a normal distribution of deviations. standard deviation standard deviation n. a quantity expressing the amount of variation or dispersion of a set of values from the mean value for the group, calculated by taking the square root of the mean of the squares of the deviations (i.e. the square root of the variance variance n. 5). ΘΚΠ the world > relative properties > number > probability or statistics > [noun] > distribution > variability or spread > measures of quartile deviation1894 standard deviation1895 s.d.1902 subrange1903 range1911 variance1918 span1962 sigma1978 1895 K. Pearson in Philos. Trans. 1894 (Royal Soc.) A. 185 75 Each component normal curve has three variables: (i.) the position of its axis, (ii.) its ‘standard-deviation’ (Gauss's ‘Mean Error’, Airy's ‘Error of Mean Square’), and (iii.) its area. 1925 R. A. Fisher Statist. Methods iii. 46 Twice the standard deviation is exceeded only about once in 22 trials. 1978 N.Z. Jrnl. Exper. Agric. 7 115/1 Suppose a large flock of sheep has weights which are normally distributed with a mean weight of 50 kg and a standard deviation of 5 kg. 2008 D. J. Hand Statistics: Very Short Introd. ii. 34 If most of the data points are clustered very closely together, with just a few outlying points, this will be recognized by the standard deviation being small. < as lemmas |
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