An Introduction to the theory of statistics

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Monograph

Identifikator:: 1751730271

URN:: urn:nbn:de:zbw-retromon-127610

Document type:: Monograph

Author:: Yule, George Udny http://d-nb.info/gnd/12910504X

Title:: An Introduction to the theory of statistics

Edition:: 8. ed. rev

Place of publication:: London

Publisher:: Griffin

Year of publication:: 1927

Scope:: XV, 422 S; Ill., Diagr

Digitisation:: 2021

Collection:: Economics Books

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Document type:: Monograph

Structure type:: Chapter

Title:: Part I. The theory of atributes

Collection:: Economics Books

I.—NOTATION AND TERMINOLOGY. J differ as to the class in which a given individual should be entered. The possibility of uncertainties of this kind should always be borne in mind in considering statistics of attributes: whatever the nature of the classification, however, natural or artificial, definite or uncertain, the final judgment must be de- cisive ; any one object or individual must be held either to possess the given attribute or not. 5. A classification of the simple kind considered, in which each class is divided into two sub-classes and no more, has been termed by logicians classification, or, to use the more strictly applicable term, division by dichotomy (cutting in two). The classifica tions of most statistics are not dichotomous, for most usually a class is divided into more than two sub-classes, but dichotomy is the fundamental case. In Chapter V. the relation of dichotomy to more elaborate (manifold, instead of twofold or dichotomous) processes of classification, and the methods applicable to some such cases, are dealt with briefly. 6. For theoretical purposes it is necessary to have some simple notation for the classes formed, and for the numbers of observa- tions assigned to each, The capitals 4, B, C, . . . will be used to denote the several attributes. An object or individual possessing the attribute 4 will be termed simply 4. The class, all the members of which possess the attribute 4, will be termed the class 4. It is con- venient to use single symbols also to denote the absence of the attributes 4, B, C, . . . We shall employ the Greek letters, a, By v» -.. Thus if A represents the attribute blindness, a represents sight, i.e. non-blindness; if B stands for deafness, 8 stands for kearing. Generally “a” is equivalent to “non-A,” or an cbject or individual not possessing the attribute A ; the class a is equivalent to the class none of the members of which possess the attribute A. 7. Combinations of attributes will be represented by juxta- positions of letters. Thus if, as above, 4 represents blindness, B deafness, AB represents the combination blindness and deafness. If the presence and absence of these attributes be noted, the four classes so formed, viz. 4B, 4f3, aB, af3, include respectively the blind and deaf, the blind but not-deaf, the deaf but not-blind, and the neither blind nor deaf. If a third attribute be noted, e.g. in- sanity, denoted say by C, the class ABC, includes those who are at once deaf, blind, and insane, 4 By those who are deaf and blind but not vnsane, and so on. Any letter or combination of letters like 4, AB, aB, ABy, by means of which we specify the characters of the members of a class, may be termed a class symbol. U

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