Evaluation of the C-BARQ as a measure of stranger-directed aggression in three common dog breeds

Volume 124, Issue 3, Pages 136-141 (May 2010) 8 of 12 Evaluation of the C-BARQ as a measure of stranger-directed aggression in three common dog breeds Stéphanie M. van den Berga, Henri C.M. Heuvenb1, Linda van den Bergc2, Deborah L. Duffyd3, James A. Serpelld3 Accepted 11 February 2010. published online 16 March 2010 Abstract Most test development in animal behaviour research is based on classical test theory. Modern test theory, also known as item-response theory, has however a number of advantages. Here, item-response theory was applied to confirm the stranger-directed aggression subscale of the Canine Behavioral Assessment and Research Questionnaire (C-BARQ). The sample consisted of a total of 1000 German Shepherds, Golden Retrievers and Labrador Retrievers. Results showed a good fit for a 1-parameter (Rasch) model. Although there were statistically significant violations of the measurement invariance assumption across breeds, the violations were only minor and without practical consequence. It is therefore concluded that the subscale consisting of 10 items can be used to quantify stranger-directed aggression in these three breeds, and that scores of different dogs can be compared meaningfully regardless of the dogs’ sex, breed or neutering status. Keywords: Item Response Theory, IRT, Rasch, C-BARQ, Canine, Aggression a University of Twente, Faculty of Behavioural Sciences, Department of Research Methodology, Measurement and Data Analysis, P.O. Box 217, 7500 AE Enschede, The Netherlands b Utrecht University, Faculty of Veterinary Medicine, Department of Clinical Sciences of Companion Animals, P.O. Box 80163, 3508 TD Utrecht, The Netherlands c Leiden University Medical Center, Department of Pediatrics and Department of Human Genetics, S4-P, P.O. Box 9600, 2300 RC Leiden, The Netherlands d University of Pennsylvania, School of Veterinary Medicine, Department of Clinical Studies VHUP, Philadelphia, PA 19104-6010, USA Corresponding author. Tel.: +31 53 489 2422; fax: +31 53 489 4239. 1 Tel.: +31 30 2539782. 2 Tel.: +31 71 526 9400. 3 Tel.: +1 21 5898 1004. PII: S0168-1591(10)00069-9 doi:10.1016/j.applanim.2010.02.005 © 2010 Elsevier B.V. All rights reserved