Die Schweiz

Factures consulaires et certificats d'origine

Bibliographic data

Monograph

Identifikator:: 1008917265

URN:: urn:nbn:de:zbw-retromon-19129

Document type:: Monograph

Author:: Flückiger, Otto http://d-nb.info/gnd/117736708

Title:: Die Schweiz

Edition:: Zweite Auflage

Place of publication:: Zürich

Publisher:: Druck und Verlag von Schultheß & Co.

Year of publication:: 1914

Scope:: 1 Online-Ressource (VI, 243 Seiten)

Digitisation:: 2017

Collection:: Economics Books

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

4 THEORY OF STATISTICS. the variables 1 and 2 can be accounted for by correlations between 1 and 3 and 2 and 3. Again, in the case of illustration iii., Chap. X., a marked positive correlation might be observed between, say, the bulk of a crop and the rainfall during a certain period, and practically no correlation between the crop and the accumulated temperature during the same period ; and the question might arise whether the last result might not be due merely to a negative correlation between rain and accumulated temperature, the crop being favourably affected by an increase of accumulated temper- ature of other things were equal, but failing as a rule to obtain this benefit owing to the concomitant deficiency of rain. In the prob- lem of inheritance in a population, the corresponding problem is of great importance, as already indicated in Chapter IV. It is essential for the discussion of possible hypotheses to know whether an observed correlation between, say, grandson and grandparent can or cannot be accounted for solely by observed correlations between grandson and parent, parent and grandparent. 2. Problems of this type, in which it is necessary to consider simultaneously the relations between at least three variables, and possibly more, may be treated by a simple and natural extension of the method used in the case of two variables. The latter case was discussed by forming linear equations between the two variables, assigning such values to the constants as to make the sum of the squares of the errors of estimate as low as possible : the more complicated case may be discussed by forming linear equations between any one of the = variables involved, taking each in turn, and the » — 1 others, again assigning such values to the constants as to make the sum of the squares of the errors of estimate a minimum. If the variables are X; X, X, . ... X,, the equation will be of the form Xi=a+b6,X, +6, X;+ .... +5,.X,. If in such a generalised regression or characteristic equation we find a sensible positive value for any one coefficient such as b,, we know that there must be a positive correlation between X, and X, that cannot be accounted for by mere correlations of Xj and X, with X,, X,, or X,, for the effects of changes in these variables are allowed for in the remaining terms on the right. The magnitude of 6, gives, in fact, the mean change in X, associated with a unit change in X, when all the remaining variables are kept constant. The correlation between X, and X, indicated by 6, may be termed a partial correlation, as corresponding with the partial association of Chapter IV., and it is required to deduce from the values of the coefficients 4, which may be termed partial regressions, partial coefficients of corre- 230

Access restriction

Copyright

Contents: Factures consulaires et certificats d'origine

Monograph

Table of contents

Download

Monograph

Chapter

This page

Image fragment

Citation links

Citation recommendation