Solution of a Ranking Problem from Binary Comparisons
Solution of a Ranking Problem from Binary Comparisons
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DOI:
10.1080/00029890.1957.11989117
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发表时间:
1957-10
影响因子:
0.5
通讯作者:
L. R. Ford
中科院分区:
文献类型:
--
作者:
L. R. Ford
1. Introduction. Occasionally one is faced with the problem of ranking a collection of objects on the basis of a number of binary comparisons, where these have not been, nor cannot be, chosen in a manner desirable to the experimenter. The standard procedures (eg, p. 217 of [1]) seem to require usually that the number of comparisons between any given pair be equal to the number between any other pair; for one reason or another it may be quite difficult in practice to achieve this equality for a suitably large sample size. For example, if one were attempting to rank various makes of automobiles by obtaining paired comparisons only from persons who have actually owned both makes one sees easily that it might be extremely difficult to obtain a large number of comparisons for such pairs as Cadillac fJersus Crosley. On the other hand, Chevrolet fJersus Ford comparisons would be available in large numbers. The method proposed in this paper does not require any specific number of comparisons between pairs, and for this reason may have some application in contexts similar to the above. Another potential application is in ranking players of a two-person game on the basis of their records against each other. In collegiate football, for example, where matches are not scheduled in a manner suited to the experimenter, this technique could be used. We assume as given a matrix A=(aiJ), where a, i represents the number of times object i has been preferred to objectj (a..= O). The approach we shall use is that of maximum likelihood. We associate with the ith object a weight w,. These weights will be interpreted as odds, in the sense that the probability of i being preferred toj in a future comparison will be taken to be w, j (w.+ w;). With these probabilities we may compute the a priori probability of obtaining precisely the matrix of results which we in fact did obtain (ie, the matrix A), under the assumption that each comparison that takes place between i and j is independent of all other comparisons, and is drawn randomly from a binomial distribution with p= w•/(w.+ w1) and with the number of ij comparisons being required to be equal to a, 1+ aii.