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 II. The theory of variables

Collection:: Economics Books

VI.—THE FREQUENCY-DISTRIBUTION. : of decimals: if the rate stated to be 16:50 proves to be 16-502, it will be sorted to the class 16:5-17°5; if 16498, to the class 155-165. Death-rates that work out to half-units exactly do not occur in this example, and so there is no real difficulty. In the case of Table II., again, there is no difficulty : if the year of birth and death alone are given, the age at death is only calcul- able to the nearest unit; if the actual day of birth and death be cited, half-years still cannot occur in the age at death, because there is an odd number of days in the year. The difficulty may always be avoided if it be borne in mind in fixing the limits to class-intervals, these being carried to a further place of decimals, or a smaller fraction, than the values in the original record. Thus if statures are measured to the nearest centimetre, the class- intervals may be taken as 1505-1515, 151'5-152°5, ete. ; if to the nearest eighth of an inch, the intervals may be 5915-6013, 6015-6118, and so on. If the difficulty is not evaded in any of these ways, it is usual to assign one-half of an intermediate observation to each adjacent class, with the result that half-units occur in the class-frequencies (¢f. Tables VIL, p. 90, X,, p. 96, and XI., p. 96). The procedure is rough, but probably good enough for practical purposes ; strict precision is usually unattainable, for in point of fact the odd way in which different individuals read a scale (¢/. Supplement I.) renders it impossible to assign exact limits to intervals. 9. Tabulation.—As regards the actual drafting of the final table, there is little to be said, except that care should be taken to express the class-limits clearly, and, if necessary, to state the manner in which the difficulty of intermediate values has been met or evaded. The class-limits are perhaps best given as in Tables I. and II, but may be more briefly indicated by the mid- values of the class-intervals. Thus Table I. might have been given in the form— Death-rate per 1000 Number of per annum to the Districts with Nearest Unit. said Death-rate, 13 5 14 16 15 61 15 112 eLc. ete. A common mode of defining the class-intervals is to state the limits in the form “az and less than .” In the case of measure- ments of stature, for example, the table micht run— 81 a

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