Notes and queries on anthropology / edited for the Council of the Anthropological Institute by John George Garson, M.D. and Charles Hercules Read, F.S.A.

Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: Notes and queries on anthropology / edited for the Council of the Anthropological Institute by John George Garson, M.D. and Charles Hercules Read, F.S.A. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

    254/272 (page 240)
    statistical law. The obvious efifect of multifariousness is to make it an extremely rare event that all or nearly all the iufJuences should be exerted in the same direction. Ex. It is a very rare event that all the cai'ds in a hand at whist are found to be of the same colour. This is a simple result of the law of permutation : there are a vast and calculable number of different events each of which is equally likely to occur, and only one of the.se is the event in question. Proceeding on this principle and making certain rather forced suppositions to render calculation feasible, the law of deviation is mathema- tically deduced ; and comparing fact with theory, wherever comparison is possible, it is found that they agree very fairly and in many cases surprisingly well. Eeasoning backwards, we may suspect that a group is not homogeneous, or that the large influences are not sufficiently subdivided into phases (refer back to 3), when it does not conform to this law. The law shows that the frequency of small deviations must be very much greater than that of large ones, and that the larger the deviation is, whether above or below the average, so the frequency of the occurrence diminishes in an accele- ratino- degree. It also shows, owing to the suppositions introduced, that the deviations on either side of the average are symmetrical ; this is rarely strictly the case m nature. Useful Data.—When collecting data of strength, stature, keenness of eye-sight, or of hearing, accuracy of aim m shootintr, or any other variable performance, a ready and efficacio^us process is to use two fixed tests in each particular, and to note the number of those who fail and of those who succeed in either test. We are able to make use of the law of deviation described in the last paragraph, and thereby to calculate with fair precision from these two d^ta, the pro- portion of those who would fail at any other test of the kind Similarly, we can calculate the value of the test t iat would be beyond the powers of just one half of those submitted to ft ; in other words, we know what won d be the average performance. Example-Sxn^^o.e strength is to be tested Select two stones and weigh them. Then offer small prizes to those who can lift both of them in succession, beginning