The story of artificial silk

An Introduction to the theory of statistics

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Monograph

Identifikator:: 1765923751

URN:: urn:nbn:de:zbw-retromon-146069

Document type:: Monograph

Author:: Casson, Herbert Newton http://d-nb.info/gnd/118814435

Title:: The story of artificial silk

Place of publication:: London

Publisher:: Efficiency Magazine

Year of publication:: [1928]

Scope:: xiii S., S. 17 - 130

Digitisation:: 2021

Collection:: Economics Books

Usage license:: Get license information via the feedback formular.

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Document type:: Monograph

Structure type:: Chapter

Title:: The story of Courtaulds and british Celanese

Collection:: Economics Books

Xv1L.—NORMAL CORRELATION. 25 and inserting o,=272, 0y= 275, r,;=051, sin f=cos §=1//2 find oz=3'361). Drawing a diagram and fitting a normal curve we have fig. 51 ; the distribution is rather irregular but the fit is fair ; certainly there is no marked asymmetry, and, so far as the graphical test goes, the distribution may be regarded as appreciably normal. One of the greatest divergences of the actual distribution from the normal curve occurs in the almost central interval with frequency 78: the difference between the observed and calculated frequencies is here 12 units, but the standard error is 9'1, so that it may well have occurred as a fluctuation of simple sampling. LA : — . 8¢ k Fie. 51.—Distribution of Frequency obtained by addition of Table III., Chap. IX., along Diagonals running up from left to right, fitted with a Normal Curve. 11. So far, we have seen (1) that the regression is approxi- mately linear; (2) that, in the arrays which we have tested, the standard-deviations are approximately constant, or at least that their differences are only small, irregular and fluctuating ; (3) that the distribution of totals for one set of diagonal arrays is approxi- mately normal. These results suggest, though they cannot completely prove, that the whole distribution of frequency may be regarded as approximately normal, within the limits of fluctu- ations of sampling. We may therefore apply a more searching test, viz. the form of the contour lines and the closeness of their fit to the contour-ellipses of the normal surface. We can see at once, however, that no very close fit can be expected. Since the frequencies in the compartments of the table are small, the standard error of any frequency is given approximately by its acy

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