Mexico

An Introduction to the theory of statistics

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Monograph

Identifikator:: 1780202415

URN:: urn:nbn:de:zbw-retromon-166228

Document type:: Monograph

Author:: Sapper, Karl http://d-nb.info/gnd/116805382

Title:: Mexico

Edition:: 2., vollst. neubearb. Aufl. der "Wirtschaftsgeographie von Mexico"

Place of publication:: Wien

Publisher:: Seidel

Year of publication:: 1928

Scope:: 164 Seiten, [8] Blätter; Ill., Kt.

Digitisation:: 2021

Collection:: Economics Books

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

Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: II. Wirtschaftsgeschichtliche Skizze

Collection:: Economics Books

204 THEORY OF STATISTICS. if the two dispersions are approximately the same, the slope of RR to the vertical is 7. Plotting the medians of arrays on a diagram with the quartile deviations as units, and measuring the slope of the line, was the method of determining the correlation coefficient (‘‘Galton’s function ”) used by Sir Francis Galton, to whom the introduction of such a coeflicient is due. (Refs. 2-4 of Chap. IX. p. 188.) (3) If s, be the standard deviation of errors of estimate like x — b,.y, we have from Chap. IX. § 11— 8a = g2{L jE v2), and hence 3,2 r= —_ a But if the dispersions of arrays do not differ largely, and the regression is nearly linear, the value of s, may be estimated from the average of the standard-deviations of a few rows, and r deter- mined—or rather estimated—accordingly. Thus in Table III, Chap. IX., the standard-deviations of the ten columns headed 625-635, 63:5-64-5, etc., are— 2:56 2-26 2-11 2-26 2:55 2-45 2:24 2:33 2:23 - = 2-60 Mean 2-359 The standard-deviation of the stature of all sons is 2:75: hence approximately ni ge “\ 275 =0514. This is the same as the value found by the product-sum method to the second decimal place. It would be better to take an average by counting the square of each standard-deviation once for each observation in the column (or * weighting” it with the number of observations in the column), but in the present case this would only lead to a very slightly different result, viz. o=2'362, r=0'512. 20. The Correlation Ratio.—The method clearly would not give an approximation to the correlation coefficient, however, in the case of such tables as V. and VI. of Chap. IX., in which the means of successive arrays do not lie closely round straight lines.

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