Personality tests often consist of a set of dichotomous or Likert items. These response formats are known to be susceptible
to an agreeing-response bias called acquiescence. The common assumption in balanced scales is that the sum of appropriately
reversed responses should be reasonably free of acquiescence. However, inter-item correlation (or covariance) matrices can
still be affected by the presence of variance due to acquiescence. To analyse these correlation matrices, we propose a method
that is based on an unrestricted factor analysis and can be applied to multidimensional scales. This method obtains a factor
solution in which acquiescence response variance is isolated in an independent factor. It is therefore possible, without the
potentially confounding effect of acquiescence, to: (a) examine the dominant factors related to content latent variables;
and (b) estimate participants–factor scores on content latent variables. This method, which is illustrated by two empirical
data examples, has proved to be useful for improving the simplicity of the factor structure.
Key words Acquiescence - balanced scales - exploratory factor analysis - factor simplicity
This research was partially supported by a grant from the Spanish Ministry of Science and Technology (SEJ2005-09170-C04-04/PSIC),
and a grant from the Catalan Ministry of Universities, the Research and Information Society (2005SGR00017). The authors are
obliged to the team of reviewers for helpful comments on an earlier version of this paper.