The Tetrad Difference Criterion


IN recent years the quantity F, called the ‘tetrad-difference’, has become very important in psychological investigations as to the possible nature of the underlying causes of mental activities. If there are four such activities, and r13, r24, etc., the six correlation coefficients, F is defined by the equation F = r13r24r14r23. The value of F, in practice, approximates to zero.

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MACKIE, J. The Tetrad Difference Criterion. Nature 120, 298 (1927).

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