Published online by Cambridge University Press: 01 January 2025
We concern ourselves with the hypothesis that two variables have a perfect disattenuated correlation, hence measure the same trait except for errors of measurement. This hypothesis is equivalent to saying, within the adopted model, that true scores of two psychological tests satisfy a perfect linear relation. Statistical tests of this hypothesis are derived when the relation is specified with the exception of the additive constant. Two approaches are presented and various assumptions concerning the error parameters are used. Then the results are reinterpreted in terms of the possible existence of an unspecified perfect linear relation between true scores of two psychological tests. A numerical example is appended by way of illustration.
Research reported in this paper has been supported by grant GB-18230 from National Science Foundation.
Throughout this paper the term “linear relation” indicates a perfect linear relationship between variables, not just linearity of regression.