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Correlation data on nine reading tests originally analyzed by Frederick B. Davis by the principal axes method are reanalyzed by Spearman's uni-dimensional method. It is concluded that a single common factor (reading ability) accounts for the correlations among the tests with residuals remarkably small in view of the fact that the tests were designed to test nine supposedly different skills. Three of the tests showed additional specific variance not attributable to the common factor.
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L. L. Thurstone (1946) studied this question.
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