The interpretation of the EPQ Lie scale scores under honest and faking instructions: A multiple-group IRT-based analysis

This study proposes and assesses a model-based general hypothesis on the interpretation of the EPQ Lie scores when obtained under standard conditions and under instructed faking. The base model is a multiple-group item-response-theory (IRT) model that is parameterized here as a factor-analytic model. A Spanish translation of the Lie scale was administered to a total group of 762 undergraduate students under standard instructions (401 respondents) and under faking-good instructions (361 respondents). Preliminary results at the total-score level were in agreement with previously reported evidence. Results obtained with the model-based analysis agreed with the general hypothesis, and suggested, among other things, that: (a) the Lie scores measure a common unitary factor under both types of conditions, (b) the measurement characteristics of the items remain essentially invariant in both conditions, and (c) the factor means change substantially in the expected direction. Limitations of the study, implications of the results, and future lines of research are discussed.