A Psychometric Theory of Evaluations of Item and Scale Translations

A psychometric theory of equivalence of meanings of items and item responses in original and target language versions of psychological scales is developed. Equivalence of translated items is defined in terms of probabilities of a specified response being evoked by two stimuli among individuals with the same amount of the latent trait assessed by the items. In the case of translated items that form psychological scales, the stimuli are the source and target language versions of the item. The specified responses are correct or positive responses to these measurement items. The extent to which items are equivalent across the different language versions can be evaluated within the framework of item response theory (Lord Smith, Kendall, & Hulin, 1969) translated into five languages and administered to approximately 3,000 employees in six countries are discussed briefly.