R. Steinmetz (Jour. Sed. Petrology, v. 32, p. 801-818, 1962), in reviewing methods used to calculate the mean direction of a set of vectors, illustrates discussion of the three-dimensional direction problem in geology by a numerical example on the mean dip and strike of sedimentary beds (cross-beds), applying the original statistical method devised by R. A. Fisher (1953) in comparison with other methods. G. S. Watson and E. Irving (1957), working with paleomagnetic data, have devised a sampling method, not mentioned in Steinmetz's review, in which more efficient analysis of data results in less uncertainty in the mean direction and in a smaller cone of confidence, and requires a smaller number of observations than the Fisher method.

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