Validation of the German Intimacy Scale

The intimacy questionnaire by Birnie (2009; Birnie-Porter & Lydon, 2013) is a promising measure of relationship intimacy due to its strong theoretical background, the inclusion of lay conceptions and the differentiation of emotional and sexual intimacy. This study aimed to validate our German translation of Birnie's questionnaire, which we labeled Intimacy Scale (IS). In two independent samples (379 and 203 individuals), confirmatory factor analyses showed best support for a bifactor S-1 model, with a strong general intimacy factor and a small specific factor, capturing unique portions of the variance related to sexual intimacy. The general intimacy factor correlated very highly and to the point of redundancy with relationship quality. Taken together, the IS may be useful as measure of relationship quality with a general (intimacy) factor. Future research is needed to improve the factorial structure of the scale.